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.math.*;
import java.util.*;
/*
public class olesyaNRodion {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		int t=sc.nextInt();
		BigInteger r=new BigInteger(0+"");
		BigInteger v;
		BigInteger k=new BigInteger(1+"");
		if (n==0 && t==10) 
			System.out.println("-1");
		else {
			int p=0;
			int x=(int)Math.pow(10,n-1);
			v=new BigInteger(x+"");
			for(int i=0;;++i) {
				if (v.mod(BigInteger.valueOf(t)).compareTo(r)==0) 
					if (v.mod(BigInteger.valueOf(10)).compareTo(r)!=0) {
						System.out.println(v);
						p=1;
						break;
					}
				v=v.add(k);
			}
			if (p==0)
				System.out.println("-1");
		}
	}
}
*/

public class olesyaNRodion {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		int t=sc.nextInt();
		String s="";
		if (t==10 && n<2)
			System.out.println("-1");
		else if (t==10 && n>=2) {
			for(int i=0;i<n-1;++i)
				s+=Integer.toString(1);
			s+=Integer.toString(0);
			System.out.println(s);
		}
		else {
			for(int i=0;i<n;++i) 
				s+=Integer.toString(t);
			System.out.println(s);
		}
	}
}