View Code of Problem 3696

#include <algorithm>
#include <cctype>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <map>
#include <set>
#include <stack>
#include <string>
#include <vector>
using namespace std;

int main(void)
{
    int n;
    while (scanf("%d",&n) != EOF)
    {
        int ans = 1;
        int tmp = n;
        n %= 10;
        while(tmp){
            if(tmp % 2 == 1){
                ans *= n;
                ans %= 10;
            }
            tmp /= 2;
            n *= n;
            n %= 10;
        }
        printf("%d\n", ans);
    }
}