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.sql.SQLOutput;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        int n , d;
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        d = sc.nextInt();
        if (d == 2 || d == 4 ||d == 8 ||d == 6){
            if(n == 1){
                if (d == 2){
                    System.out.print("2");
                }
                if (d == 4){
                    System.out.print("4");
                }
                if (d == 8){
                    System.out.print("8");
                }
                if (d == 6){
                    System.out.print("6");
                }
                System.exit(0);
            }
            else if (n == 2 && d == 8){
                System.out.print(16);
                System.exit(0);
            }
            for(int i = 1; i <= n-2; i++){
                System.out.print("3");
            }
            System.out.print("12");
        }
        if (d == 5 || d == 10){
            if (n == 1 && d == 5){
                System.out.print(5);
                System.exit(0);
            }
            if (n == 1 && d == 10){
                System.out.print(-1);
                System.exit(0);
            }
            for(int i = 1; i <= n-1; i++){
                System.out.print("5");
            }
            System.out.print("0");
        }
        if (d == 3){
            for(int i = 1; i <= n; i++){
                System.out.print("3");
            }
        }
        if (d == 9){
            for(int i = 1; i <= n; i++){
                System.out.print("9");
            }
        }
        if (d == 7){
            for(int i = 1; i <= n; i++){
                System.out.print("7");
            }
        }

        //System.out.println(four + " " + dv + " " );
    }
}