简洁题解
import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long a = sc.nextLong(),b = sc.nextLong(),p = sc.nextLong();
        long ans = 1%p;
        for(;b!=0;b>>=1){
            if((b&1)==1) ans = (long) ans *a %p;
            a = a*a %p;
        }
        System.out.println(ans);
    }
}