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.util.Scanner;

public class Olesya {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int t = sc.nextInt();
        if(N==1 && t ==10){
            System.out.println(-1);
            return;
        }
        String str= "1";
        for(int i=0;i<N-1;i++){
            str+="0";
        }
        String q = str +"0";
        
        BigInteger value = new BigInteger(str);
        BigInteger finalVal = new BigInteger(q);
        
        for(BigInteger k= value;k.compareTo(finalVal) < 0;k = k.add(BigInteger.ONE)){
            
            if(k.mod(BigInteger.valueOf(t)).compareTo(BigInteger.ZERO) == 0){
                System.out.println(k);
                return;
            }
        }
        System.out.println(-1);

    }

}