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.util.*;
import java.math.*;
public class Main{
    public static void main(String[] afzalkhan){
        Scanner sc = new Scanner(System.in);
        long N = sc.nextInt();
        long K = sc.nextInt();
        String number = "1";
        for(int i=1;i<N;i++){
            number = number + "0";
        }
        String limit = number + "0";
        BigInteger Aa = BigInteger.valueOf(0);
        BigInteger Bb = BigInteger.valueOf(0);
        Aa = Aa.add(new BigInteger(number));
        Bb = Bb.add(new BigInteger(limit));
        BigInteger a ;
        while(!Aa.equals(Bb)){
            a = Aa.remainder(BigInteger.valueOf(K));
            if(a.equals(BigInteger.ZERO)){
               System.out.println(Aa);
               return;
            }
            Aa = Aa.add(BigInteger.ONE);

        }
        System.out.println(-1);
    }
}