好嘛，快速幂都考，下一个是不是单调栈了。

#include <iostream>
#include <string>

using namespace std;

int main()
{
	string x;
	long long y = 0, z = 0;
	while (cin >> x >> y >> z) {
		int sum = 0, ans = 1;
		for (int i = 0;i < x.size();i++) {
			sum = (sum * 10 + x[i] - '0') % z;
		}
		int xi = sum;
		while (y) {
			if (y % 2 == 1) {
				ans = (ans * xi) % z;
			}
			xi = xi * xi % z;
			y /= 2;
		}
		cout << ans % z << endl;
	}
	return 0;
}