#include <bits/stdc++.h>

using namespace std;

using ll = long long;

const int mod = 1e9 + 7;
int norm(int x) { return x >= mod ? x - mod : x; }
int reduce(int x) { return x < 0 ? x + mod : x; }
int neg(int x) { return x ? mod - x : 0; }
int quo2(int x) { return (x + (x & 1 ? mod : 0)) >> 1; }
void add(int &x, int y) { if ((x += y - mod) < 0) x += mod; }
void sub(int &x, int y) { if ((x -= y) < 0) x += mod; }
int mpow(int a, int b) {
  int ret = 1;
  for (; b; b >>= 1) {
    if (b & 1) ret = (ll)ret * a % mod;
    a = (ll)a * a % mod;
  }
  return ret;
}

const int N = 2e3 + 2;

int n, s, t;
int a, b, c;

bool vis[N + 5];
int prime[N + 5], cnt;
int aPool[N + 5], bPool[N + 5], cPool[N + 5];
int *aPow = aPool + 1, *bPow = bPool + 1, *cPow = cPool + 1;
int fac[N + 5], ifac[N + 5];
int binom(int n, int m) { return n < m || n < 0 ? 0 : (ll)fac[n] * ifac[m] % mod * ifac[n - m] % mod; }
int f[N + 5], delta0, delta1;
int ans;

int main() {
  scanf("%d%d%d", &n, &s, &t);
  if (s == t) { puts("0"); return 0; }
  if (s < t) swap(s, t);
  a = t - 1, b = s - t - 1, c = n - s, n -= 2;

  aPow[-1] = a & 1 ? mod - 1 : 1, bPow[-1] = b & 1 ? mod - 1 : 1, cPow[-1] = c & 1 ? mod - 1 : 1,
  aPow[0] = !a, bPow[0] = !b, cPow[0] = !c,
  aPow[1] = bPow[1] = cPow[1] = 1;
  for (int i = 2; i <= n + 1; ++i) {
    if (!vis[i]) prime[++cnt] = i, aPow[i] = mpow(i, a), bPow[i] = mpow(i, b), cPow[i] = mpow(i, c);
    for (int j = 1; j <= cnt && i * prime[j] <= n; ++j) {
      vis[i * prime[j]] = 1,
      aPow[i * prime[j]] = (ll)aPow[i] * aPow[prime[j]] % mod,
      bPow[i * prime[j]] = (ll)bPow[i] * bPow[prime[j]] % mod,
      cPow[i * prime[j]] = (ll)cPow[i] * cPow[prime[j]] % mod;
      if (!(i % prime[j])) break;
    }
  }
  fac[0] = 1;
  for (int i = 1; i <= n + 2; ++i) fac[i] = (ll)fac[i - 1] * i % mod;
  ifac[n + 2] = mpow(fac[n + 2], mod - 2);
  for (int i = n + 2; i; --i) ifac[i - 1] = (ll)ifac[i] * i % mod;
  for (int i = 0; i <= n + 2; ++i) {
    if (i) sub(f[i], f[i - 1]);
    if (i > 1) sub(f[i], quo2(f[i - 2]));
    if (i <= 1) add(f[i], 1);
    if (i == n + 1) delta0 = neg(f[i]), f[i] = 0;
    if (i == n + 2) delta1 = neg(f[i]);
  }

  for (int i = 0; i <= n; ++i) {
    f[i] = ((ll)(mod - delta0) * binom(n + 1, i) + (ll)delta1 * binom(n + 2, i)) % mod;
    if ((n ^ i) & 1) f[i] = neg(f[i]);
    if (i == 1) add(f[i], 1);
    if (i > 1) sub(f[i], f[i - 2]);
    if (n & 1) ans = (ans + ((ll)(mod - aPow[i + 1]) * cPow[i + 1] + (ll)aPow[i - 1] * cPow[i - 1]) % mod * bPow[i] % mod * f[i]) % mod;
    else ans = (ans + ((ll)aPow[i + 1] * cPow[i - 1] + (ll)aPow[i - 1] * cPow[i + 1]) % mod * bPow[i] % mod * f[i]) % mod;
  }
  if (((n + 1) >> 1) & 1) ans = neg(ans);
  printf("%d\n", ans);
}