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.*;
import java.io.*;
import java.math.BigInteger;
public class Main {

    public static void main(String[] args) throws Exception {
BufferedReader br = new BufferedReader(new InputStreamReader( System.in));
String[] parts=br.readLine().split(" ");
int n=Integer.parseInt(parts[0]);
int t=Integer.parseInt(parts[1]);
String start="1";
String end="9";
for(int i=0;i<n-1;i++){
    start+="0";
    end+="9";
}
//int startI=Integer.parseInt(start);
BigInteger startI=new BigInteger(start);
BigInteger endI=new BigInteger(end);

//System.out.println("s:"+startI+"    "+endI);
while(  startI.compareTo(endI)<=0){
    if(     startI.mod(BigInteger.valueOf(t)).equals(BigInteger.ZERO)){
        System.out.println(startI.toString());
        return;
    }

    startI=startI.add(BigInteger.ONE);
}



System.out.println("-1");
br.close();
}//end of main function
}//end of Main class