func_code_string: #include <bits/stdc++.h>   using namespace std;   inline int read() {     int x = 0, fl = 1;     char st = getchar();     while (st <  0  || st >  9 ) {       if (st ==  - ) fl = -1;       st = getchar();     }     while (st >=  0  && st <=  9 ) x = x * 10 + st -  0 , st = getchar();     return x * fl;   }   const int N = 1e6 + 10, mod = 1e9 + 9;   int n, b, w;   long long ans, fac[8005], invfac[8005];   inline long long ksm(long long x, long long y) {     long long res = 1;     while (y) {       if (y & 1) res = res * x % mod;       x = x * x % mod;       y >>= 1;     }     return res;   }   inline long long C(int x, int y) {     return fac[x] * invfac[y] % mod * invfac[x - y] % mod;   }   int main() {     ans = 1;     n = read();     w = read();     b = read();     fac[0] = 1;     fac[1] = 1;     for (int i = 2; i <= 8000; i++) fac[i] = fac[i - 1] * i % mod;     invfac[0] = invfac[1] = 1;     invfac[8000] = ksm(fac[8000], mod - 2);     for (int i = 7999; i >= 2; i--) {       invfac[i] = invfac[i + 1] * (i + 1) % mod;     }     ans = fac[w] * fac[b] % mod;     ans = ans * (w - 1) % mod;     ans = ans * C(w + b - 3, n - 3) % mod;     printf( %lld , ans);     return 0;   }   