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;
import java.math.BigInteger;
import java.util.StringTokenizer;

public class Oleysha{
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BigInteger ans,pot;
        String t,t2;
        int n,zero=0;
        t = br.readLine();
        StringTokenizer st = new StringTokenizer(t);
        n = Integer.valueOf(st.nextToken());
        t2 = st.nextToken();
        if(n==1 && t2.equals("10")){
            System.out.println("-1");
        }
        else {
            ans = new BigInteger(t2);
            pot = new BigInteger("10");
            pot = ans.multiply(pot);
            for(int i=pot.toString().length()-1; i>=0; i--){
                if(pot.toString().charAt(i)== '0'){
                    zero++;
                }
            }
            pot = new BigInteger("10");
            pot = pot.pow(n-zero);
            ans = ans.multiply(pot);
            System.out.println(ans);
        }
    }
}