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.util.*;
public class A{

public static void main(String args[]){

Scanner sc=new Scanner(System.in);

int n=sc.nextInt();
int t=sc.nextInt();

if(t==10){

if(n==1)
System.out.println(-1);
else
{
String s="";
while(s.length()<n-1){
s=s+"1";
}
s=s+"0";
System.out.println(s);
}
}
else{
String b="";
while(b.length()<n){
b=b+String.valueOf(t);
}
System.out.println(b);

}

}
}