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;
multiset<long long> s, ss;
map<pair<long long, int>, pair<bool, bool>> m;
vector<long long> vec, v;
bitset<26> bs;
int main() {
  bool r = false;
  string str, stb;
  long long n, t, s = 0, tmp, a[1001], b[1001], c[1001];
  cin >> n >> t;
  if (n == 1 && t >= 10) {
    cout << -1;
    return 0;
  }
  cout << t;
  s = (n - to_string(t).length());
  while (s--) cout << 0;
}