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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;


public class OlesyaAndRodion {

	public static void main(String[] args)throws IOException {
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

		String str=br.readLine();
		String arr[]=str.split(" ");
		long n=Long.parseLong(arr[0]);
		long t=Long.parseLong(arr[1]);
		String number="";
		if(n==1){
			if(n*t<10){

				System.out.println(n*t);
				return;
			}else {
				System.out.println("-1");
				return;
			}
		}
		
		if(t<10){
			for(long i=0;i<n;i++){
		
			number=number+t;
		}
		}else{
			for(long i=0;i<n-1;i++){
				
				number=number+1;
			}
			number=number+"0";
		}
		
		//long num=Long.parseLong(number);

		System.out.println(number);
}

}