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.math.BigInteger;
import java.util.Scanner;

public class Driver584A {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String str=in.nextLine();
        String[] a= str.split(" ");
        int num=Integer.parseInt(a[0]);
        int num2=Integer.parseInt(a[1]);
//        boolean b=false;
//        for(long i=(long)Math.pow(10,num-1);i<Math.pow(10,num);i++){
//            if(i%num2==0){
//                String str2=i+"";
//                //str2=str2.substring(0,str2.length()-2);
//                i=(long)Math.pow(10,num)+1;
//                b=true;
//                System.out.println(str2);
//            }
//
//        }
//        if(!b){
//            System.out.println("-1");
//        }
        str="";
        if(num2==2){
            str+="2";
            for(int i=0;i<num-1;i++){
                str+="0";
            }
        }
        else if(num2==3){
            str+="3";
            for(int i=0;i<num-1;i++){
                str+="0";
            }
        }
        else if(num2==4){
            str+="4";
            for(int i=0;i<num-1;i++){
                str+="0";
            }
        }
        else if(num2==5){
            str+="5";
            for(int i=0;i<num-1;i++){
                str+="0";
            }
        }
        else if(num2==6){
            str+="6";
            for(int i=0;i<num-1;i++){
                str+="0";
            }
        }
        else if(num2==7){
            str+="7";
            for(int i=0;i<num-1;i++){
                str+="0";
            }
        }
        else if(num2==8){
            str+="8";
            for(int i=0;i<num-1;i++){
                str+="0";
            }
        }
        else if(num2==9){
            str+="9";
            for(int i=0;i<num-1;i++){
                str+="0";
            }
        }
        else if(num2==10&&num>1){
            str+="1";
            for(int i=0;i<num-1;i++){
                str+="0";
            }
        }
        else{
            str="-1";
        }
        System.out.println(str);

    }
}