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 CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e6 + 7;
string a[7];
void init() {
  a[1] = "Sheldon";
  a[2] = "Leonard";
  a[3] = "Penny";
  a[4] = "Rajesh";
  a[5] = "Howard";
}
int main() {
  int n, t;
  cin >> n >> t;
  string s;
  if (t == 10) {
    if (n == 1) {
      cout << -1 << endl;
      return 0;
    }
    for (int i = 0; i < n; i++) {
      if (i == 0)
        s += '1';
      else
        s += '0';
    }
  } else {
    for (int i = 0; i < n; i++) {
      s += (char)('0' + t);
    }
  }
  cout << s << endl;
  return 0;
}