func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 4000 + 5, mod = 1000000009;   int n, x, y;   long long P[N], d[N][N];   int main() {     scanf( %d , &n);     scanf( %d , &x);     scanf( %d , &y);     for (int i = 0; i <= max(x, y); i++) d[i][0] = 1;     for (int i = 1; i <= max(x, y); i++)       for (int j = 1; j <= min(n, i); j++)         d[i][j] = (d[i - 1][j] + d[i - 1][j - 1]) % mod;     P[0] = 1;     for (int i = 1; i <= max(x, y); i++) P[i] = (P[i - 1] * i) % mod;     long long ans = 0;     for (int l = 2; l <= n - 1; l++)       for (int r = l; r <= n - 1; r++)         ans = (ans + (d[y - 1][r - l] * d[x - 1][n - (r - l + 2)]) % mod) % mod;     ans = ans * ((P[x] * P[y]) % mod) % mod;     printf( %I64d n , ans);     return 0;   }   