#include #include using mint = atcoder::modint1000000007; using namespace std; const int MAX = 510000; const int MOD = 1000000007; mint fac[MAX], finv[MAX], inv[MAX]; void COMinit() { fac[0] = fac[1] = 1; finv[0] = finv[1] = 1; inv[1] = 1; for (int i = 2; i < MAX; i++){ fac[i] = fac[i - 1] * i; inv[i] = MOD - inv[MOD%i] * (MOD / i); finv[i] = finv[i - 1] * inv[i]; } } mint COM(int n, int k){ if (n < k) return 0; if (n < 0 || k < 0) return 0; return fac[n] * finv[k] * finv[n - k]; } int main() { int n, m; cin >> n >> m; COMinit(); mint ans = 1; for (int i = 1; i <= m; i++){ ans *= i; } ans *= COM(n, m); cout << ans.val() << endl; }