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.*;
    import java.io.*;

    public class Codeforces {
        
        
        public static void main(String[] args) throws IOException {
            Reader.init(System.in);
            int n = Reader.nextInt();
            int t = Reader.nextInt();
            
            if(n == 1 && t == 10){
                System.out.println("-1");
                return;
            }
            
            StringBuilder ans = new StringBuilder();
            ans.append(t);
            while(ans.length() < n){
                ans.append(0);
            }
            
            System.out.println(ans);
        }
    }
    
    class  Edge implements Comparable<Edge>{

        int to;
        int from;
        int cost;
        
        Edge(int a, int b, int c){
            from = a;
            to = b;
            cost = c;
        }

        @Override
        public int compareTo(Edge t) {
            return t.cost - cost;
        }
    }


    class NN implements Comparable<NN>{
        int x;
        int mod;
        
        NN(int a, int b){
            x = a;
            mod = b;
        }

        @Override
        public int compareTo(NN t) {
            return mod - t.mod;
        }
        
    }


    class Reader {

        static BufferedReader reader;
        static StringTokenizer tokenizer;

        public static int pars(String x) {
            int num = 0;
            int i = 0;
            if (x.charAt(0) == '-') {
                i = 1;
            }
            for (; i < x.length(); i++) {
                num = num * 10 + (x.charAt(i) - '0');
            }

            if (x.charAt(0) == '-') {
                return -num;
            }

            return num;
        }

        static void init(InputStream input) {
            reader = new BufferedReader(
                    new InputStreamReader(input));
            tokenizer = new StringTokenizer("");
        }

        static void init(FileReader input) {
            reader = new BufferedReader(input);
            tokenizer = new StringTokenizer("");
        }

        static String next() throws IOException {
            while (!tokenizer.hasMoreTokens()) {
                tokenizer = new StringTokenizer(
                        reader.readLine());
            }
            return tokenizer.nextToken();
        }

        static int nextInt() throws IOException {
            return pars(next());
        }

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

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