https://www.acwing.com/problem/content/1383/

#include<bits/stdc++.h>
using namespace std;


const long long int N=1e4;
long long int n;


int main(){
    cin>>n;
    long long b=1;
    for(long long int i=n;i>=1;i--)
    {
        //long long int b;
        if((i*b)%N!=0)b=(i*b)%N;
        else {
            b=i*b;
            while(!(b%N))
            {
                b=b/N;
            }
        }

    }
    while(b%10==0)b/=10;
    cout<<b%10<<endl;
    return 0;
}