源代码 82分

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'

const int N = 205;

int n;

signed main()
{
    cin >> n;
    cout << n * (n - 1) * (n - 2) * (n - 3) / 2 / 3 / 4 << endl;
    return 0;
}

AC 代码

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'

const int N = 205;

int n;

signed main()
{
    cin >> n;
    cout << n * (n - 1) / 2 * (n - 2) / 3 * (n - 3) / 4 << endl;
    return 0;
}