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...);
}
int main() {
  int n, t;
  RI(n, t);
  if (n == 1 && t == 10) {
    puts("-1");
    return 0;
  }
  if (n == 1) {
    printf("%d\n", t);
    return 0;
  }
  int r = 0;
  for (int i = 0; i < int(n - 1); i++) {
    putchar('1');
    r = (r * 10 + 1) % t;
  }
  r = r * 10 % t;
  printf("%d\n", (t - r) % t);
  return 0;
}