简单的快速幂取模

#include <iostream>
#include <cstdio>
using namespace std;

#define  LL long long

LL  pow_mod(LL  a, LL  b)
{
LL  ans = 1;
a = a % 10;
while (b > 0)
{
if (b %2)
ans = ans * a % 10;
b= b >> 1;
a = a * a % 10;
}
return ans;
}

int main()
{
LL a, b;
while (cin >> a >> b)
{
cout << pow_mod(a, b)<< endl;
}
return 0;
}