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.*;
public class fiveEightFourA{
	public static void main(String args[]){
		Scanner x = new Scanner(System.in);
		int n = x.nextInt();
		int t = x.nextInt();
		String temp = "";
		switch( t ){
			case 2:
			case 5:
				if( n == 1 ){
					temp += Integer.toString( t );
				} else {
					temp += "1";
					while( temp.length() != n )
						temp += "0";
				}
				break;
		 	case 10:
				if( n == 1 ){
					temp = "-1";
				} else {
					temp = "1";
					while( temp.length() != n )
						temp += "0";
				}
				break;
			case 3:
				if( n == 1 ){
					temp = "3";
				} else if ( n == 2 ){
					temp = "12";
				} else {
					temp = "1";
					while( temp.length() != (n - 1) )
						temp += "0";
					temp += "2";
				}
				break;
			case 6:
				if( n == 1 )
					temp = "6";
				else{
					temp = "1";
					while( temp.length() != (n - 1) )
						temp += "0";
					temp += "2";
				}
				break;
			case 9:
				if( n == 1 ){
					temp = "9";
				} else {
					temp = "1";
					while( temp.length() != (n - 1) )
						temp += "0";
					temp += "8";
				}
				break;
			case 4:
				if( n == 1 ){
					temp = "4";
				}
				else if( n == 2 ){
					temp = "12";
				} else {
					temp = "1";
					while( temp.length() != (n - 1) )
						temp += "0";
					temp += "4";
				}
				break;
			case 7:
				temp = "7";
				while( temp.length() != (n) )
					temp += "7";
				break;
			case 8:
				temp = "8";
				while( temp.length() != (n) )
					temp += "8";
				break;
		// 	case 8:
		// 		long index = 0;
		// 		while( low <= high ){
		// 			if( low % t == 0 ){
		// 				temp = low;
		// 				break;
		// 			}
		// 			low++;
		// 		}
		// 		break;
		}

		System.out.print( temp );
	}
}