Problem: 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

Solution (in JAVA):

Solution:
import java.math.BigInteger;
import java.io.*;
import java.util.*;
import java.lang.*;


public class Main {
/* UVa 10235 - Simply Emirp */
public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    int t = sc.nextInt();
    BigInteger BN = BigInteger.valueOf(N);
    BigInteger T = BigInteger.valueOf(t);
    BigInteger ten = BigInteger.valueOf(10);
    BigInteger zero = BigInteger.valueOf(0);
    BigInteger one = BigInteger.valueOf(1);
    BigInteger o = ten.pow(N-1);
    int flag = 0;
    if(N == 1 && t == 10){
        System.out.println(-1);
        return;
    }
    for(int i = 0; i < 10; i++){
        o = o.add(one);
        if(o.mod(T).equals(zero)){
            System.out.println(o);
            flag = 1;
            break;
        }
    }
    if(flag == 0) System.out.println(-1);
    }
}