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(n>=1){
        	if(t==10)n--;
        for (int i = 0; i < n-1; i++) {
            res=res+"0";
        }
        
        System.out.println(t+res);
            
        }
        else if(n==1 && t==10) {
            System.out.println("-1");
        }
    }
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);
}

}