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>
const int maxn = 1e5 + 6;
const int modn = 1e9 + 7;
using namespace std;
int main() {
  int n, t;
  string s, r;
  cin >> n >> t;
  if (t < 10) {
    stringstream ss;
    ss << t;
    r = ss.str();
    for (int i = 1; i <= n; i++) {
      s += r;
    }
    cout << s << endl;
  } else if (t == 10 && n > 1) {
    for (int i = 1; i < n; i++) s += "1";
    s += "0";
    cout << s << endl;
  } else
    cout << "-1" << endl;
}