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.*;

public class Problem41 {

	public static void main(String[] args) {
		
		Scanner read=new Scanner(System.in);
		int n=read.nextInt();
		int t=read.nextInt();
		if(t==10 && n==1) {
			System.out.print("-1");	
		}else {
			if(t!=10) {
				System.out.print(t);
				for(int i=0 ; i<n-1 ; i++) {
					System.out.print("0");
				}
				
			}else {
				System.out.print(t);
				for(int i=0 ; i<n-2 ; i++) {
					System.out.print("0");
				}
				
			}
		}
	}
}