题目来源
Fedya studies in a gymnasium. Fedya’s maths hometask is to calculate the following expression:
(1^n?+?2^n?+ ?3^n ?+ ?4^n) mod 5
for given value of n. Fedya managed to complete the task. Can you? Note that given number n can be extremely large (e.g. it can exceed any integer type of your programming language).
Input
The single line contains a single integer n (0?≤?n?≤?1e105). The number doesn’t contain any leading zeroes.
Output
Print the value of the expression without leading zeros.
Examples
Input
4
Output
4
Input
124356983594583453458888889
Output
0
题意
对于每个输入的n, 输出取模的结果， （n非常大，只能用char数组来存）
解法
不难发现当 n%4==0时， 取模结果为4， 其余情况为0（打个表找下规律或者自己手算一下就可以发现了），而对于n的整百部分， 一定可以被4整除，判断一下最后两位就可以了
代码
#include <iostream>
#include <cstring>
using namespace std;char s[1000005];
int main(){cin >> s;int len = strlen(s);int k;if(len >=2) k = (s[len-2] -'0')*10 + s[len-1] - '0';else k = s[len-1]-'0';if(k%4==0) cout << 4 << endl;else cout << 0 << endl;return 0;
}