#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")

#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 <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; }

////////////////////////////////////////////////////////////////////////////////
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; }
};
////////////////////////////////////////////////////////////////////////////////

constexpr unsigned MO = 998244353;
using Mint = ModInt<MO>;


// Sum[(x - t) (y - t) t^2, {t, 1, s}]
inline Mint func(Mint x, Mint y, Mint s) {
  return s * (1+s) * (-2 + 2*s + 18*s*s + 12*s*s*s - 15*s*x -
      15*s*s*x - 15*s*y - 15*s*s*y + 10*x*y + 20*s*x*y)
      / 60;
}

// \sum[1<=t] max{X + 1 - t, 0} max{Y + 1 - t, 0} t^2
Mint calc2(Int X, Int Y) {
  return func(X + 1, Y + 1, min(X, Y));
}

// \sum[1<=a<=P] \sum[1<=b<=Q] max{Y + 1 - (a+b), 0} (a+b)^2
Mint calc1(Int P, Int Q, Int Y) {
  // \sum[A<=t] (t - A + 1) max{Y + 1 - t, 0} t^2
  auto sub = [&](Int A) -> Mint {
    if (A > Y) return 0;
    return -(func(A - 1, Y + 1, Y) - func(A - 1, Y + 1, A - 1));
  };
  Mint ret = 0;
  ret += sub(  1 +   1);
  ret -= sub(  1 + Q+1);
  ret -= sub(P+1 +   1);
  ret += sub(P+1 + Q+1);
  return ret;
}

// \sum[1<=a<=P] \sum[1<=b<=Q] \sum[1<=c<=R] \sum[1<=d<=S] [b-a = d-c] (b-a)(d-c)
Mint calc0(Int P, Int Q, Int R, Int S) {
  const Int lim = max(P + Q, R + S);
  // sum[A<=t && B<=t] (t - A + 1) (t - B + 1) t^2
  auto sub = [&](Int A, Int B) -> Mint {
    if (max(A, B) > lim) return 0;
    return func(A - 1, B - 1, lim) - func(A - 1, B - 1, max(A, B) - 1);
  };
  Mint ret = 0;
  for (int h = 0; h < 1 << 4; ++h) {
    Int A = 0, B = 0;
    A += ((h >> 0 & 1) ? (P+1) : 1);
    A += ((h >> 1 & 1) ? (Q+1) : 1);
    B += ((h >> 2 & 1) ? (R+1) : 1);
    B += ((h >> 3 & 1) ? (S+1) : 1);
    ret += (__builtin_parity(h)?-1:+1) * sub(A, B);
  }
  return ret;
}


int M, N, K;
vector<int> X, Y;

int main() {
  for (; ~scanf("%d%d%d", &M, &N, &K); ) {
    X.resize(K);
    Y.resize(K);
    for (int k = 0; k < K; ++k) {
      scanf("%d%d", &X[k], &Y[k]);
    }
    
    vector<int> ks(K);
    for (int k = 0; k < K; ++k) {
      ks[k] = k;
    }
    sort(ks.begin(), ks.end(), [&](int k0, int k1) -> bool {
      return ((Y[k0] != Y[k1]) ? (Y[k0] < Y[k1]) : (X[k0] < X[k1]));
    });
    
    auto ms = X;
    ms.push_back(0);
    ms.push_back(M);
    sort(ms.begin(), ms.end());
    ms.erase(unique(ms.begin(), ms.end()), ms.end());
    const int msLen = ms.size();
    
    Mint ans = 0;
    int len;
    vector<int> xs(K + 2), ys(K + 2);
    vector<int> prv(K + 2), nxt(K + 2);
    for (int e = 0; e < msLen - 1; ++e) {
      // x1 < xR <= x2
      const int x1 = ms[e];
      const int x2 = ms[e + 1];
// cerr<<"("<<x1<<", "<<x2<<"]"<<endl;
      
      // Case. x1 <= xL
      {
        const Mint res = calc2(x2 - x1, N);
        ans += res;
/*
Mint brt=0;
for(int a=x1;a<=x2;++a)for(int b=a+1;b<=x2;++b)
 for(int c=0;c<=N;++c)for(int d=c+1;d<=N;++d)
  if(b-a==d-c)brt+=(b-a)*(d-c);
cerr<<"  #"<<__LINE__<<": "<<brt<<" "<<res<<endl;
assert(brt==res);
//*/
      }
      
      len = 0;
      xs[0] = 0;
      ys[0] = 0;
      for (const int k : ks) if (X[k] <= ms[e]) {
        ++len;
        xs[len] = X[k];
        ys[len] = Y[k];
      }
      xs[len + 1] = 0;
      ys[len + 1] = N;
// cerr<<len<<" "<<xs<<" "<<ys<<endl;
      for (int i = 1; i <= len; ++i) {
        int &j = prv[i] = i - 1;
        for (; j >= 1 && xs[j] <= xs[i]; j = prv[j]) {}
      }
      for (int i = len; i >= 1; --i) {
        int &j = nxt[i] = i + 1;
        for (; j <= len && xs[j] < xs[i]; j = nxt[j]) {}
      }
      
      // no left bound
      for (int i = 0; i <= len; ++i) {
        // x0 <= xL < x1 < xR <= x2 && y0 <= yL < yR <= y2
        const int x0 = 0;
        const int y0 = ys[i];
        const int y2 = ys[i + 1];
        const Mint res = calc1(x1 - x0, x2 - x1, y2 - y0);
        ans += res;
/*
Mint brt=0;
for(int a=x0;a<x1;++a)for(int b=x1+1;b<=x2;++b)
 for(int c=y0;c<=y2;++c)for(int d=c+1;d<=y2;++d)
  if(b-a==d-c)brt+=(b-a)*(d-c);
cerr<<"  #"<<__LINE__<<" "<<x0<<" "<<y0<<" "<<y2<<": "<<brt<<" "<<res<<endl;
assert(brt==res);
//*/
      }
      for (int i = 1; i <= len; ++i) {
        // ks[i] decides the left bound
        // x0 <= xL < x1 < xR <= x2 && y0 <= yL < y1 < yR <= y2
        const int x0 = xs[i];
        const int y0 = ys[prv[i]];
        const int y1 = ys[i];
        const int y2 = ys[nxt[i]];
        const Mint res = calc0(x1 - x0, x2 - x1, y1 - y0, y2 - y1);
        ans += res;
/*
Mint brt=0;
for(int a=x0;a<x1;++a)for(int b=x1+1;b<=x2;++b)
 for(int c=y0;c<y1;++c)for(int d=y1+1;d<=y2;++d)
  if(b-a==d-c)brt+=(b-a)*(d-c);
cerr<<"  #"<<__LINE__<<" "<<x0<<" "<<y0<<" "<<y1<<" "<<y2<<": "<<brt<<endl;
assert(brt==res);
//*/
      }
    }
    
    printf("%u\n", ans.x);
  }
  return 0;
}