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 main() {
  long long int n, t, i, c = 0, s, x, y, u;
  cin >> n >> t;
  if (t < 10) {
    for (i = 0; i < n; i++) cout << t;
  } else {
    s = t / 10;
    c++;
    while (1) {
      s = s / 10;
      c++;
      if (s == 0) break;
    }
    if (c == n)
      cout << t;
    else if (c > n)
      cout << "-1";
    else if (c < n) {
      u = n - c;
      cout << t;
      for (i = 1; i <= u; i++) cout << 0;
    }
  }
  return 0;
}