#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

using Int = long long;

template <class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &a) { return os << "(" << a.first << ", " << a.second << ")"; };
template <class T> ostream &operator<<(ostream &os, const vector<T> &as) { const int sz = as.size(); os << "["; for (int i = 0; i < sz; ++i) { if (i >= 256) { os << ", ..."; break; } if (i > 0) { os << ", "; } os << as[i]; } return os << "]"; }
template <class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; }
template <class T> bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; }
template <class T> bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; }
#define COLOR(s) ("\x1b[" s "m")

////////////////////////////////////////////////////////////////////////////////
template <unsigned M_> struct ModInt {
  static constexpr unsigned M = M_;
  unsigned x;
  constexpr ModInt() : x(0U) {}
  constexpr ModInt(unsigned x_) : x(x_ % M) {}
  constexpr ModInt(unsigned long long x_) : x(x_ % M) {}
  constexpr ModInt(int x_) : x(((x_ %= static_cast<int>(M)) < 0) ? (x_ + static_cast<int>(M)) : x_) {}
  constexpr ModInt(long long x_) : x(((x_ %= static_cast<long long>(M)) < 0) ? (x_ + static_cast<long long>(M)) : x_) {}
  ModInt &operator+=(const ModInt &a) { x = ((x += a.x) >= M) ? (x - M) : x; return *this; }
  ModInt &operator-=(const ModInt &a) { x = ((x -= a.x) >= M) ? (x + M) : x; return *this; }
  ModInt &operator*=(const ModInt &a) { x = (static_cast<unsigned long long>(x) * a.x) % M; return *this; }
  ModInt &operator/=(const ModInt &a) { return (*this *= a.inv()); }
  ModInt pow(long long e) const {
    if (e < 0) return inv().pow(-e);
    ModInt a = *this, b = 1U; for (; e; e >>= 1) { if (e & 1) b *= a; a *= a; } return b;
  }
  ModInt inv() const {
    unsigned a = M, b = x; int y = 0, z = 1;
    for (; b; ) { const unsigned q = a / b; const unsigned c = a - q * b; a = b; b = c; const int w = y - static_cast<int>(q) * z; y = z; z = w; }
    assert(a == 1U); return ModInt(y);
  }
  ModInt operator+() const { return *this; }
  ModInt operator-() const { ModInt a; a.x = x ? (M - x) : 0U; return a; }
  ModInt operator+(const ModInt &a) const { return (ModInt(*this) += a); }
  ModInt operator-(const ModInt &a) const { return (ModInt(*this) -= a); }
  ModInt operator*(const ModInt &a) const { return (ModInt(*this) *= a); }
  ModInt operator/(const ModInt &a) const { return (ModInt(*this) /= a); }
  template <class T> friend ModInt operator+(T a, const ModInt &b) { return (ModInt(a) += b); }
  template <class T> friend ModInt operator-(T a, const ModInt &b) { return (ModInt(a) -= b); }
  template <class T> friend ModInt operator*(T a, const ModInt &b) { return (ModInt(a) *= b); }
  template <class T> friend ModInt operator/(T a, const ModInt &b) { return (ModInt(a) /= b); }
  explicit operator bool() const { return x; }
  bool operator==(const ModInt &a) const { return (x == a.x); }
  bool operator!=(const ModInt &a) const { return (x != a.x); }
  friend std::ostream &operator<<(std::ostream &os, const ModInt &a) { return os << a.x; }
};
////////////////////////////////////////////////////////////////////////////////

template <unsigned M_> struct ModInv {
  static constexpr unsigned M = M_;
  int k, k2, l;
  vector<int> qs;
  vector<ModInt<M>> inv;
  ModInv() {
    k = cbrt(M);
    k2 = k * k;
    l = M / k;
    qs.assign(k2 + 1, 0);
    for (int q = k; q >= 1; --q) for (int p = 0; p <= q; ++p) qs[k2 * p / q] = q;
    for (int i = 1; i <= k2; ++i) if (!qs[i]) qs[i] = qs[i - 1];
    inv.assign(l + 1, 0);
    inv[1] = 1;
    for (int i = 2; i <= l; ++i) inv[i] = -((M / i) * inv[M % i]);
  }
  ModInt<M> operator()(ModInt<M> a) const {
    const double r = static_cast<double>(k2) * a.x / M;
    const int q0 = qs[r];
    const ModInt<M> b0 = a * q0;
    if (b0.x <= static_cast<unsigned>(l)) return inv[b0.x] * q0;
    const int q1 = qs[k2 - r];
    return -inv[(-a * q1).x] * q1;
  }
};

// 0 = \sum_{j=0}^d (\sum_{k=0}^e css[j][k] i^k) as[i - j]  (d <= i < |as|)
template <unsigned M>
vector<vector<ModInt<M>>> findPRecurrence(const vector<ModInt<M>> &as, int e,
                                          bool verbose = false) {
  using Mint = ModInt<M>;
  const int asLen = as.size();
  // asLen - d >= (d + 1) (e + 1) - 1  (otherwise definitely  dim Ker >= 2)
  const int d0 = (asLen + 2) / (e + 2) - 1;
  if (d0 < 0) {
    if (verbose) {
      fprintf(stderr, "[findPRecurrence] |as| >= e  must hold.\n");
      fflush(stderr);
    }
    return {};
  }
  const int m = asLen - d0, n = (d0 + 1) * (e + 1);
  vector<vector<Mint>> bss(m, vector<Mint>(n, 0));
  for (int i = d0; i < asLen; ++i) for (int j = 0; j <= d0; ++j) {
    Mint pw = 1;
    for (int k = 0; k <= e; ++k) {
      bss[i - d0][j * (e + 1) + k] = pw * as[i - j];
      pw *= i;
    }
  }
  int r = 0;
  vector<int> hs;
  for (int h = 0; h < n; ++h) {
    for (int i = r; i < m; ++i) if (bss[i][h]) {
      bss[r].swap(bss[i]);
      break;
    }
    if (r < m && bss[r][h]) {
      const Mint s = bss[r][h].inv();
      for (int j = h; j < n; ++j) bss[r][j] *= s;
      for (int i = 0; i < m; ++i) if (i != r) {
        const Mint t = bss[i][h];
        for (int j = h; j < n; ++j) bss[i][j] -= t * bss[r][j];
      }
      ++r;
    } else {
      hs.push_back(h);
    }
  }
  if (hs.empty()) {
    if (verbose) {
      fprintf(stderr, "[findPRecurrence] Not found: d = %d, e = %d.\n", d0, e);
      fflush(stderr);
    }
    return {};
  }
  vector<vector<Mint>> css(d0 + 1, vector<Mint>(e + 1, 0));
  for (int j = 0; j <= d0; ++j) for (int k = 0; k <= e; ++k) {
    const int h = j * (e + 1) + k;
    css[j][k] = (h < hs[0]) ? -bss[h][hs[0]] : (h == hs[0]) ? 1 : 0;
  }
  int d = hs[0] / (e + 1);
  for (int i = d0; i < asLen; ++i) {
    Mint sum = 0;
    for (int j = 0; j <= d0; ++j) {
      Mint coef = 0, pw = 1;
      for (int k = 0; k <= e; ++k) {
        coef += css[j][k] * pw;
        pw *= i;
      }
      sum += coef * as[i - j];
    }
    for (; sum; ) {
      if (i - ++d < 0) break;
      assert(d <= d0);
      Mint coef = 0, pw = 1;
      for (int k = 0; k <= e; ++k) {
        coef += css[d][k] * pw;
        pw *= i;
      }
      sum += coef * as[i - d];
    }
  }
  css.resize(d + 1);
  if (verbose) {
    const int hsLen = hs.size();
    if (hsLen > d0 - d + 1) {
      fprintf(stderr, "[findPRecurrence] Degenerate? (dim Ker = %d)\n", hsLen);
    }
    fprintf(stderr, "[findPRecurrence] d = %d, e = %d, non-trivial: %d\n", d, e,
            asLen - d - (d + 1) * (e + 1) + 1);
    fprintf(stderr, "{\n");
    for (int j = 0; j <= d; ++j) {
      fprintf(stderr, "  {");
      for (int k = 0; k <= e; ++k) {
        const unsigned c = css[j][k].x;
        if (k > 0) fprintf(stderr, ", ");
        fprintf(stderr, "%d", static_cast<int>((c < M - c) ? c : (c - M)));
      }
      fprintf(stderr, "},\n");
    }
    fprintf(stderr, "}\n");
    fflush(stderr);
  }
  return css;
}

// 0 = \sum_{j=0}^d (\sum_{k=0}^e css[j][k] i^k) as[i - j]  (d <= i < |as|)
template <unsigned M>
vector<ModInt<M>> extendPRecurrence(vector<ModInt<M>> as,
                                    const vector<vector<ModInt<M>>> &css,
                                    int n) {
  using Mint = ModInt<M>;
  static const ModInv<M> modInv;
  assert(!css.empty());
  const int d = css.size() - 1, e = css[0].size() - 1;
  for (int j = 0; j <= d; ++j) assert(static_cast<int>(css[j].size()) == e + 1);
  const int asLen = as.size();
  as.resize(n);
  for (int i = asLen; i < n; ++i) {
    Mint sum = 0;
    for (int j = 1; j <= d; ++j) {
      Mint coef = 0, pw = 1;
      for (int k = 0; k <= e; ++k) {
        coef += css[j][k] * pw;
        pw *= i;
      }
      sum += coef * as[i - j];
    }
    {
      Mint coef = 0, pw = 1;
      for (int k = 0; k <= e; ++k) {
        coef += css[0][k] * pw;
        pw *= i;
      }
      // as[i] = -sum / coef;
      as[i] = -sum * modInv(coef);
    }
  }
  return as;
}

////////////////////////////////////////////////////////////////////////////////


constexpr unsigned MO = 1004535809;
using Mint = ModInt<MO>;

constexpr int LIM_INV = 1010;//10'000'010;
Mint inv[LIM_INV], fac[LIM_INV], invFac[LIM_INV];

void prepare() {
  inv[1] = 1;
  for (int i = 2; i < LIM_INV; ++i) {
    inv[i] = -((Mint::M / i) * inv[Mint::M % i]);
  }
  fac[0] = invFac[0] = 1;
  for (int i = 1; i < LIM_INV; ++i) {
    fac[i] = fac[i - 1] * i;
    invFac[i] = invFac[i - 1] * inv[i];
  }
}
Mint binom(Int n, Int k) {
  if (n < 0) {
    if (k >= 0) {
      return ((k & 1) ? -1 : +1) * binom(-n + k - 1, k);
    } else if (n - k >= 0) {
      return (((n - k) & 1) ? -1 : +1) * binom(-k - 1, n - k);
    } else {
      return 0;
    }
  } else {
    if (0 <= k && k <= n) {
      assert(n < LIM_INV);
      return fac[n] * invFac[k] * invFac[n - k];
    } else {
      return 0;
    }
  }
}

////////////////////////////////////////////////////////////////////////////////


int N;
Mint P, Q;
vector<int> U, V;

// [z^m] ((1-P)z/(1-Pz))^(a+b-1) (1 + z/(1-Pz))
Mint brute(int u, int v) {
  if (u == 0 && v == 0) return 1;
  Mint ret = 0;
  for (int m = 0; m <= u && m <= v; ++m) {
    const int a = u - m, b = v - m;
    if (a+b <= 0) break;
    auto at = [&](int n) -> Mint {
      return (n >= a+b-1) ? (binom(n, a+b-1) * P.pow(n - (a+b-1))) : 0;
    };
    ret += binom(a+b, a) * Q.pow(a) * (1-Q).pow(b) * (1-P).pow(a+b-1) * (at(m) + (1-P) * at(m-1));
  }
  return ret;
}

int main() {
  prepare();
  
#ifdef LOCAL
/*
P=Q=inv[2];
for(int u=0;u<=10;++u){
 for(int v=0;v<=10;++v){
  int q=1<<20;
  int p=(brute(u,v)*q).x;
  const int g=__gcd(p,q);p/=g;q/=g;
  cerr<<p<<"/"<<q<<" ";
 }
 cerr<<endl;
}
//*/
/*
P=12;Q=34;
for(int c=0;c<=20;++c){
 cerr<<endl<<"c = "<<c<<endl;
 vector<Mint>fs(200);
 for(int i=0;i<200;++i)fs[i]=brute(i,c+i);
 for(int e=1;e<=1;++e)findPRecurrence(fs,e,true);
}
//*/
#endif
  
  for (; ~scanf("%d%u%u", &N, &P.x, &Q.x); ) {
    U.resize(N);
    V.resize(N);
    for (int n = 0; n < N; ++n) {
      scanf("%d%d", &U[n], &V[n]);
    }
    
    /*
    Mint ans = 0;
    for (int n = 0; n < N; ++n) ans += brute(U[n], V[n]);
    printf("%u\n", ans.x);
    */
    
    constexpr int L = 100;
    vector<Mint> fs(L);
    for (int i = 0; i < L; ++i) fs[i] = brute(i, i);
    const auto coef = findPRecurrence(fs, 1, true);
    fs = extendPRecurrence(fs, coef, 10'000'010);
    
    Mint ans = 0;
    for (int n = 0; n < N; ++n) ans += fs[U[n]];
    printf("%u\n", ans.x);
  }
  return 0;
}