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;
void RI() {}
template <typename... T>
void RI(int& head, T&... tail) {
  scanf("%d", &head);
  RI(tail...);
}
mt19937 rng(0x5EED);
int randint(int lb, int ub) {
  return uniform_int_distribution<int>(lb, ub)(rng);
}
int N, T;
int main(int argc, char** argv) {
  cin >> N >> T;
  if (T == 10) {
    if (N == 1) {
      puts("-1");
    } else {
      for (int i = 1; i < N; i++) putchar('1');
      puts("0");
    }
  } else {
    for (int i = 0; i < N; i++) putchar('0' + T);
    puts("");
  }
  return 0;
}