RE求助

/*
    Ryan_L_F专属签名（防盗）
    lalalalalala~~
    I'm ambition is AK IOI
*/

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e5 + 10, mod = 1e9; 
int n;
ll sum = 1, ans, A[N], out[N];

int main(){
    scanf("%d", &n);
    A[0] = 1;
    for(int i = 1; i < n; i++){
        int u, v; scanf("%d %d", &u, &v);

        A[i] = A[i - 1] * i % mod;
        out[u] ++, out[v] ++;
    }
    A[n] = A[n - 1] * n % mod;

    for(int i = 1; i <= n; i++) sum = sum * A[out[i] - 1] % mod;

    for(int i = 1; i <= n; i++){
        ll cnt = sum / A[out[i] - 1] * A[out[i]] % mod;
        ans = (ans + cnt) % mod;
    }

    printf("%d", ans);
    return 0;
}