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() {
  int n, i;
  cin >> n >> i;
  if (n == 1 && i != 10)
    cout << i;
  else if (n == 1 && i == 10)
    cout << -1;
  else if (i == 4 || i == 8) {
    cout << 4;
    for (i = 1; i < n; i++) cout << 0;
  } else if (i == 7) {
    cout << 7;
    for (i = 1; i < n; i++) cout << 0;
  } else {
    cout << 9;
    for (i = 1; i < n; i++) cout << 0;
  }
}