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 CF584_D2_A_OlesyaAndRodion {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt(), t = sc.nextInt();
        
        if(n==1) {
            if(t<10)
                System.out.println(t);
            else
                System.out.println(-1);
        }else {
            String s = "1";
            for (int i = 1; i < n; i++) {
                s = s+"0";
            }
            
            BigInteger b = new BigInteger(s);
            BigInteger T = new BigInteger(t+"");
            
            while(!b.mod(T).equals(BigInteger.ZERO)){
                b=b.add(BigInteger.ONE);
            }
            
            System.out.println(b);    
        }
        
        
    }

}