Codeforce 584A - Olesya and Rodion

Olesya loves numbers consisting of n digits, and Rodion only likes numbers that are divisible by t. Find some number that satisfies both of them.

Your task is: given the n and t print an integer strictly larger than zero consisting of n digits that is divisible by t. If such number doesn't exist, print - 1.

Input

The single line contains two numbers, n and t (1 ≤ n ≤ 100, 2 ≤ t ≤ 10) — the length of the number and the number it should be divisible by.

Output

Print one such positive number without leading zeroes, — the answer to the problem, or  - 1, if such number doesn't exist. If there are multiple possible answers, you are allowed to print any of them.

Examples

input

3 2

output

712

#include <iostream>
#include <stdio.h>
#include <algorithm>
#include <cstring>
#include <sstream>
using namespace std;
const int maxn = 1e9+10;
#define N 10005
int main()
{
        int n,t,i;
        scanf("%d %d", &n, &t);
        if(n==1&&t==10){
            printf("-1\n");
        }
        else{
            if(t==10){
                t=1;
            }
            printf("%d",t);
            for(i=0;i<n-1; i++)  {
                printf("0");
            }
            printf("\n");
        }
    return 0;
}