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:
//package com.company;
import java.util.Arrays;
import java.util.Scanner;
public class Main {

    public static void main(String[] args) {


        Scanner input = new Scanner(System.in);
        int length= input.nextInt();
        int division= input.nextInt();

        if (division==2){
            for (int i=0;i<length;i++){
                System.out.print("2");
            }
        }else if(division==3){
            for (int i=0;i<length;i++){
                System.out.print("3");
            }
        }else if(division==4){
            for (int i=0;i<length;i++){
                System.out.print("4");
            }
        }else if(division==5){
            for (int i=0;i<length;i++){
                System.out.print("5");
            }
        }else if(division==6){
            for (int i=0;i<length;i++){
                System.out.print("6");
            }
        }else if(division==7){
            for (int i=0;i<length;i++){
                System.out.print("7");
            }
        }else if(division==8){
            for (int i=0;i<length;i++){
                System.out.print("8");
            }
        }else if(division==9){
            for (int i=0;i<length;i++){
                System.out.print("9");
            }
        }else if(division==10){
            if (length>=2){
                for (int i=0;i<length-1;i++){
                    System.out.print("1");
                }
                System.out.print("0");
            }else {
                System.out.print("-1");
            }

        }


    }
}
/*

*/