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.*;
import java.util.*;
public class Codeforce {

    static int mod = (int) (1e9 + 7);

    public static class pair implements Comparator<pair> {
        int x;
        int y;

        public pair() {

        }

        public pair(int x, int y) {
            this.x = x;
            this.y = y;

        }

        @Override
        public int compare(pair o1, pair o2) {
            return o1.y - o2.y;
        }
    }
    public static long modularpow(long a,long b){
        long res=1;
        if(b==0)
            return res;
        else
        {
            while(b>0){
                if(b%2==1){
                    res*=a;
                    res%=mod;

                }
                a=a*a;
                a%=mod;
                b/=2;
            }
            return res%mod;
        }
    }
  public static int gcd(int a,int b){
        if(b==0)
            return a;
        else
            return gcd(b,a%b);
  }


    public static void main(String arg[]) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter sb = new BufferedWriter(
                new OutputStreamWriter(System.out));
        int t =1;
        while (t-- > 0) {

            String s[] = br.readLine().split(" ");
            int n = Integer.parseInt(s[0]);
            int x = Integer.parseInt(s[1]);
            if (n == 1 && x == 10)
                sb.write("-1");
            else {

                String s1 ="";
                if(x==10)
                    s1+="1";
                else
                    s1+=String.valueOf(x);
                for (int i = 2; i <= n; i++)
                    s1 += "0";
                sb.write(s1);
            }
        }
        sb.flush();
    }
}