187版本

#include <iostream>
#include <cassert>
using namespace std;
typedef long long ll;
ll a, b, p;
ll quick_power(ll a,ll b){ //计算a的b次方
    if(b == 0) return 1;
    ll ans = quick_power(a,b/2); //先计算a的（b / 2）次方
    ans = ans * ans % p;           
    if(b % 2 == 1){                //如果 b 是奇数，则 a ^ b = (a ^ (b / 2))  * (a ^ (b / 2)) * a
        return ans*a % p;
    }
    return ans;
}
int main() {
    cin >> a >> b >> p;
    cout << a << "^" << b << " mod " << p << "=" <<quick_power(a,b);
    return 0;
}