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.util.*;

public class Main {
    private static final FastReader scanner = new FastReader();

    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(
                    new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }

    private static final StringBuilder outputBuilder = new StringBuilder();
    public static void appendAns(Object o) {
        outputBuilder.append(o.toString());
    }
    public static void appendAnsLine(Object o) {
        outputBuilder.append(o.toString()).append("\n");
    }
    public static void appendAnsLine() {
        outputBuilder.append("\n");
    }
    public static void printAns() {
        System.out.println(outputBuilder);
    }

    // START //

    public static void solve() {
        int n = scanner.nextInt();
        int t = scanner.nextInt();

        if (n == 1 && t == 10) {
            appendAns("-1");
            return;
        }

        if (t == 10) {
            appendAns(1);
            for (int i = 1; i < n; i++) {
                appendAns("0");
            }
        } else {
            for (int i = 0; i < n; i++) {
                appendAns(t);
            }
        }
    }

    public static void main(String[] args) {
        //int testCount = scanner.nextInt();
        int testCount = 1;

        for (int t = 0; t < testCount; t++) {
            solve();
        }

        printAns();
    }
}