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 dp[1024][1024];
bool prime(long long int n) {
  if (n < 0) return 0;
  if (n % 2 == 0) return n == 2;
  for (int i = 3; i * i <= n; i++)
    if (n % i == 0) return 0;
  return 1;
}
int main() {
  int n, k;
  cin >> n >> k;
  if (n == 1 && k == 10)
    cout << "-1\n";
  else {
    if (k == 10)
      cout << k / 10;
    else
      cout << k;
    for (int i = 1; i < n; i++) cout << 0;
    cout << endl;
  }
}