const int N = 5010;
const int mod = 1e9 + 7;

int f[N], rf[N];

int powmod(int a, int p) {
    if (p == 0) return 1;
    if (p == 1) return a;
    int k = powmod(a, p / 2);
    if (p & 1) return (k * k % mod) * a % mod;
    return k * k % mod;
}

int rev(int x) {
    return powmod(x, mod - 2);
}

int C(int n, int k) {
    int ans = f[n];
    ans = ans * rf[k] % mod;
    ans = ans * rf[n - k] % mod;
    return ans;
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    f[0] = 1;
    for (int i = 1; i < N; i++) {
        f[i] = f[i - 1] * i % mod;
    }
    rf[N - 1] = rev(f[N - 1]);
    for (int i = N - 1; i > 0; i--) {
        rf[i - 1] = rf[i] * i % mod;
    }
}