龟速乘
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll a,b,p;
int main(){
scanf("%lld%lld%lld",&a,&b,&p);
ll res = 0;
while(b){
if(b&1)res = (res + a) % p;
a = (a << 1) % p;
b >>= 1;
}
printf("%lld\n",res);
}