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.math.*;
import java.lang.*;

public class Code {

	static Scanner sr = new Scanner(System.in);

	public static void main(String[] args) {

		int numberLength = sr.nextInt();
		int divider = sr.nextInt();
		
		StringBuilder sb = new StringBuilder();
		sb.append("1");
		for (int i = 0; i < numberLength - 1; i++) {
			sb.append("0");
		}
		
		BigInteger value = new BigInteger(sb.toString(), 10);
		BigInteger result = new BigInteger(sb.toString(), 10);
		
		boolean needCicle = true;
		if (divider == 10)
			needCicle = false;
		for (int i = 2; (i <= 9) && needCicle; i++) {
			result = result.add(value);
			if(result.mod(BigInteger.valueOf(divider)) == BigInteger.valueOf(0)) break;
		}
		if(numberLength == 1 && divider == 10) System.out.println("-1");
		else
		System.out.println(result);
	}
}