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 = 1e6;
const int MOD = 1e9 + 7;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int N, T;
  cin >> N >> T;
  if (T == 10 && N == 1) {
    cout << -1;
    return 0;
  }
  if (T != 10) {
    for (int i = 0; i < N; i++) cout << T;
  }
  if (T == 10) {
    for (int i = 0; i < N - 1; i++) cout << 1;
    cout << 0;
  }
  return 0;
}