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 A584 {
	public static void main(String[] args) throws Exception {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		
		StringTokenizer st = new StringTokenizer(in.readLine());		
		
		int len = Integer.parseInt(st.nextToken());
		int div = Integer.parseInt(st.nextToken());	

		if(div % 5 == 0) {
			if(len == 1) {
				if(div == 5) {
					System.out.print(5);
				} else {
					System.out.print(-1);
				}
			} else {
				System.out.print(1);
				printloop(0, len - 1);
			}
		} else if(div % 2 == 0 && div % 3 != 0) {
			printloop(8, len);
		} else if(div % 3 == 0) {
			if(div % 2 != 0) {
				printloop(9, len);
			} else {
				printloop(6, len);
			} 
 		} else {
 			printloop(7, len);
 		}

 		System.out.println();
	}

	public static void printloop(int val, int num) {
		for(int i = 0; i < num; i++) {
			System.out.print(val);
		}
	}

}