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.Scanner;

public class Codeforceseasy {

    //    1333A
//    public static void main(String[] args) {
//        Scanner sc = new Scanner(System.in);
//        int t = sc.nextInt();
//        while (t-- > 0) {
//            int n = sc.nextInt();
//            int m = sc.nextInt();
//            char[][] ch = new char[n][m];
//            ch[0][0] = 'W';
//            for (int i = 0; i < n; i++) {
//                for (int j = 0; j < m; j++) {
//                    if (ch[i][j] != 'W')
//                        ch[i][j] = 'B';
//                }
//            }
//            for (int i = 0; i < n; i++) {
//                for (int j = 0; j < m; j++) {
//                    System.out.print(ch[i][j] + " ");
//                }
//                System.out.println();
//            }
//        }
//    }


    //    public static void main(String[] args) {
//        Scanner sc = new Scanner(System.in);
//        int t = sc.nextInt();
//        while (t-- > 0) {
//            long a = sc.nextInt();
//            long b = sc.nextInt();
//            long n = sc.nextInt();
//            long s = sc.nextInt();
//            int f = 0;
//            long rem = s % n;
////            System.out.println(rem + " " + b + " " + s / n + " " + a);
//            if (rem <= b && (a * n) + b >= s)
//                f = 1;
//            if (f == 0)
//                System.out.println("NO");
//            else System.out.println("YES");
//        }
//    }
//    public static void main(String[] args) {
//        Scanner sc = new Scanner(System.in);
//        int t = sc.nextInt();
//        while (t-- > 0) {
//            long a = sc.nextLong();
//            long b = sc.nextLong();
//            if (b == 1)
//                System.out.println("NO");
//            else {
//                System.out.println("YES");
//                System.out.println(a * b + " " + a + " " + a * (b + 1));
//            }
//        }
//    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long tt = sc.nextInt();
        long n = sc.nextInt();
        if (tt == 1 && n == 10) {
            System.out.println("-1");
            return;

        }
        StringBuilder stb = new StringBuilder();
        if (n != 10) {
            stb.append(n);
            for (int i = 0; i < tt - 1; i++) {
                stb.append("0");
            }
            System.out.println(stb);
        } else {
            stb.append("1");
            for (int i = 0; i < tt - 1; i++) {
                stb.append("0");
            }
            System.out.println(stb);
        }
    }
}