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;
unsigned long long x, y, z;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  string ans;
  cin >> x >> y;
  if (y < 10) {
    ans = to_string(y);
    while (x != 1) {
      ans += to_string(y);
      x--;
    }
    cout << ans << endl;
  } else {
    if (x == 1)
      cout << -1 << endl;
    else {
      ans = "10";
      while (x != 2) {
        ans += "0";
        x--;
      }
      cout << ans << endl;
    }
  }
}