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.Scanner;

public class olesya
{
    public static void main(String args[])
    {
    Scanner s = new Scanner(System.in);

    int n = s.nextInt();
    int m = s.nextInt();

    if(n==1)
    {       
        if(m<10)
        {
            System.out.println(m);
            return;
        }
        else
        {
            System.out.println(-1);
            return;
        }
    }
    else
    {
        System.out.print(1);
        for(int i=1;i<n-1;i++)
        {
            System.out.print(0);
        }
        switch(m)
        {
        case(2): System.out.print(0);
            return;
        case(3):System.out.print(2);
            return;
        case(4):
            if(n==2)
            System.out.print(2);
            else
            System.out.print(0);
            return;
        case(5): System.out.print(0);
            return;
        case(6):System.out.print(2);
            return;
        case(7):
            if((n-1)%6==0)
            System.out.print(6);
            else if((n-1)%6==1)
            System.out.print(4);
            else if((n-1)%6==2)
            System.out.print(5);
            else if((n-1)%6==3)
            System.out.print(1);
            else if((n-1)%6==4)
            System.out.print(3);
            else if((n-1)%6==5)
            System.out.print(2);
            return;
        case(8):
            if(n==2)
            System.out.print(6);
            else if(n==3)
            System.out.print(4);
            else 
            System.out.print(0);
            return;
        case(9):System.out.print(8);
            return;
        case(10): System.out.print(0);
            return;
        }
    }
    }
}