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.*;

public class OlesyaAndRodion {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] input =  br.readLine().split("\\s+");
        int digits = Integer.parseInt(input[0]);
        int div = Integer.parseInt(input[1]);
        if(div == 10) {
            if(digits == 1) {
                System.out.println("-1");
            }else{
                System.out.println(div + getZeros(digits-2));
            }
        } else{
            System.out.println(div + getZeros(digits-1));
        }
    }

    private static String getZeros(int n){
        StringBuilder sb = new StringBuilder();
        for(int i= 0; i<n; i++){
            sb.append("0");
        }
        return sb.toString();
    }
}