信奥赛1172

#include <bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin>>n;
    vector<int> a;
    a.push_back(1);
    int j;
    for(int g = 2;g<=n;g++){
        for(int i = 0;i<a.size() || j;i++){
            if(i>=a.size()){
                a.push_back(0);
            }
            j += a[i]*g;
            a[i] = j%10;
            j /= 10;
        }
    }
    for(int i = a.size()-1;i>=0;i--){
        cout<<a[i];
    }
    return 0;
}