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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class OlesyaAndRodion {

	public static void main(String[] args) throws IOException {
		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
		
		String[] ss = bf.readLine().split(" ");
		int n = Integer.parseInt(ss[0]);
		int t = Integer.parseInt(ss[1]);
		
		if(n==1){
			if(t==10){
				System.out.print("-1");
			}else{
				System.out.print(t);	
			}
			
		}
		else{
			if(t==10){
				for(int i=1;i<n;i++){
					System.out.print("1");
				}
				System.out.print("0");
			}
			else{
				for(int i=1;i<=n;i++){
					System.out.print(t);
				}				
			}
		}
		System.out.println();		
	}

}