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.io.*;
public class test{
	public static void main(String[] args) {
		Scanner sc= new Scanner(System.in);
		int n = sc.nextInt();
		int t = sc.nextInt();
		if(n > 1){
			if(t < 10){
				while(n-- > 0){
					System.out.print(t);
				}
			}else{
				if(t < 100 && t >= 10){
					System.out.print(t);
					int k = n-2;
					while(k-- > 0){
						System.out.print(0);
					}
				}
				if(t == 100){
					System.out.print(t);
					int k = n-3;
					while(k-- > 0){
						System.out.print(0);
					}
				}
			}
			System.out.println();
		}
		if(n==1){
			if(t < 10)System.out.println(t);
			else System.out.println(-1);				
		}
	}
}