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.InputStreamReader;
import java.math.BigInteger;

public class Main {
	public static void main(String[] args)throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] in = br.readLine().split(" ");
		int n = Integer.parseInt(in[0]) ;
		BigInteger num = new BigInteger("1");
		BigInteger zero = new BigInteger("0");
		BigInteger t = new BigInteger(in[1]);
		boolean flag=false;
		for(int i=0;i<n-1;i++)
			num=num.multiply(new BigInteger("10"));
		if(Integer.parseInt(in[1])==2){
			flag=true;
			if(n==1)
				num = new BigInteger("2");
		}
		while(true && !flag){
			if(num.mod(t).compareTo(zero)==0 && num.toString().length()==n){
				flag=true;
				break;
			}
			else{
				num=num.add(t.subtract(num.mod(t)));
			}
			if(num.toString().length()!=n )
				break;
		}
		if(!flag)
			System.out.println(-1);
		else
			System.out.println(num);
	}
}