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.util.StringTokenizer;

public class OlsRod {
	public static void satisfy(int n,int t){
		String res = "";
		if(t==10)n--;
		for (int i = 0; i < n-1; i++) {
			res=res+"0";
		}

		System.out.println(t+res);

	}


	public static void main(String[] args) throws Throwable {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());

		int n= new Integer(st.nextToken());
		int t= new Integer(st.nextToken());
		if(n==1&&t==10){
			System.out.println("-1");
			return;
		}
		satisfy(n,t);
	}

}