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;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;
	
	public class A584 {
		BufferedReader br;
		StringTokenizer in;
		PrintWriter out;
		
		public String nextToken() throws IOException {
		    while (in == null || !in.hasMoreTokens()) {
		        in = new StringTokenizer(br.readLine());
		    }

		    return in.nextToken();
		}

		public int nextInt() throws IOException {
		    return Integer.parseInt(nextToken());
		}

		public long nextLong() throws IOException {
		    return Long.parseLong(nextToken());
		}

		public double nextDouble() throws IOException {
		    return Double.parseDouble(nextToken());
		}
		
		public void solve() throws IOException {
			br = new BufferedReader(new InputStreamReader(System.in));
	        out = new PrintWriter(System.out);
	       
	        int n = nextInt();
	        
	        int t = nextInt();
	        
	        if(n == 1 && t == 10) {
	        	out.println(-1);
	        	out.close();
	        	return;
	        }
	        out.print(t);
	        int length = 1;
	        if(t == 10)
	        	length = 2;
	        while(length != n) {
	        	out.print(0);
	        	length++;
	        }
	        out.println();
 	        out.close();
		}
		
		public int gcd(int m, int n){
			if(m == 0)
				return n;
			return gcd(n % m, m);
		}
		
		public static void main (String [] args) throws IOException {
			new A584().solve();
			}
	}