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.IOException;
import java.io.InputStreamReader;


public class Main {

    static int sz(int a){
        int s = 0;
        while( a > 0 ){
            s++;
            a = a / 10;
        }
        return s;
    }
    
    public static void main(String[] args) throws IOException {
        // TODO Auto-generated method stub
        BufferedReader in = new BufferedReader( new InputStreamReader(System.in) );
        String data[] = in.readLine().split(" ");
        int n = Integer.parseInt(data[0]);
        int t = Integer.parseInt(data[1]);
        if( String.valueOf(t).length() > n ){
            System.out.println(-1);
            System.exit(0);
        }
        String xd = t + "";
        if( t == 10 ) n--;
        for(int i=1; i<n; i++){
            xd += "0";
        }
        
        System.out.println(xd);
    }
}