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 = 100005;
const int mod = (int)1e9 + 7;
char a[maxN];
int main() {
  int n, t;
  cin >> n >> t;
  if (n == 1) {
    if (t <= 9) {
      cout << t << endl;
    } else {
      cout << -1 << endl;
    }
    return 0;
  }
  int mod = 0;
  for (int i = 0; i < n - 1; ++i) {
    cout << 1;
    mod = (mod * 10 + 1) % t;
  }
  for (int dig = 0; dig < 10; ++dig) {
    if ((mod * 10 + dig) % t == 0) {
      cout << dig << endl;
      return 0;
    }
  }
  cout << -1 << endl;
}