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.Arrays;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.util.Scanner;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.TreeSet;
import java.io.BufferedReader;
import java.util.StringTokenizer;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;
public class OlesyaandRodion {
	
	public static void main(String[] args) throws IOException {
		PrintWriter pw=new PrintWriter(System.out);
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st=new StringTokenizer(br.readLine());
		int x=Integer.parseInt(st.nextToken());
		int y=Integer.parseInt(st.nextToken());
		if(y>=2 && y<10) {
			String z="";
			while(x>0) {
				z+=y;
				x--;
			}
			pw.print(z);
		}else if (y==10) {
			if(x==1)
				pw.print(-1);
			else {
				String z="";
				while(x>1) {
					z+=1;
					x--;
				}
				pw.print(z+"0");
			}
		}
		pw.println();
		pw.flush();
		pw.close();
	}

}