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.BigInteger;
import java.util.Scanner;

public class Demo {
	public static void main(String[] args) {
	
		Scanner sc = new Scanner(System.in);
		BigInteger n = sc.nextBigInteger();
		int t= sc.nextInt();
		String str = "";
		boolean flag = true;
		for(BigInteger bn = BigInteger.ZERO;n.compareTo(bn)>0;bn=bn.add(BigInteger.ONE)){
		//System.out.println(n.toString()+""+bn.toString());	
			if(flag){
				str = "1";
				flag = false;
				continue;
			}
			str = str+"0";
		}
		BigInteger start = new BigInteger(str);
		String len = "";
		BigInteger tl = new BigInteger(""+t);
		boolean found = false;
		while(len.length()<str.length()+1){
			if(start.mod(tl)==BigInteger.ZERO){
				System.out.println(start.toString());
				found = true;
				break;
			}
			start = start.add(BigInteger.ONE);
			len = start.toString();
		}
		if(!found){
			System.out.println("-1");
		}
	}
}