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.io.PrintWriter;
import java.math.BigInteger;
import java.util.*;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
public class JavaApplication12 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int n = input.nextInt(), t = input.nextInt();
        // String num = input.next(); 
        String str = "";
        if (n==1&&t==10){
            System.out.println(-1);
            System.exit(0);
        }
        if (t==10){
            str="1";
            for (int i = 1; i < n; i++) {
                str=str+0;
            }
            System.out.println(str);
            System.exit(0);
        }
        if (n==1&&t<10){
            System.out.println(t);
            System.exit(0);
        }
        for (int i = 0; i < n; i++) {
            str=str+t;
        }
        System.out.println(str);
    }
}