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.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.Set;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int t = sc.nextInt();
		
		StringBuilder N = new StringBuilder("1");
		for(int i = 0; i < n-1; i++) N.append(0);
		BigInteger num = new BigInteger(N.toString());
		BigInteger other = new BigInteger(t + "");
		while(!num.mod(other).equals(BigInteger.ZERO)) {
			num = num.add(BigInteger.ONE);
		}
		if(num.toString().length() == n)
			System.out.println(num);
		else 
			System.out.println(-1);

		
	}
}