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;
int n, t;
int main() {
  cin >> n >> t;
  long long z = pow(10, n - 2);
  if (n == 1 and t == 10) return cout << -1 << endl, 0;
  if (n == 1) return cout << t << endl, 0;
  if (t == 2 or t == 4 or t == 5 or t == 8 or t == 10)
    cout << 40;
  else if (t == 7)
    cout << 14;
  else
    cout << 18;
  n -= 2;
  while (n) {
    cout << '0';
    n--;
  }
  cout << endl;
}