#include<bits/stdc++.h>
using namespace std;
int main(){
	long long w;
	int n,h,j=INT_MAX;
	cin>>n>>h;
	w=pow(n,h);
	if(n>10&&h>10){
		cout<<"-1";
	}else if(w<j){
		cout<<w;	
	} else{
		cout<<"-1";
	} 
	return 0;
}
/**************************************************************
	Problem: 2405
	User: houshanglin
	Language: C++
	Result: Accepted
	Time:32 ms
	Memory:2324 kb
****************************************************************/