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 task();
int main() {
  task();
  return 0;
}
const int N = (int)1e5 + 10;
const long long int MODULO = (long long int)1e9 + 7;
const int INF = INT_MAX;
const int BUF_SIZE = (int)1e4 + 10;
int n, t;
void task() {
  scanf("%d %d", &n, &t);
  if (n == 1 && t == 10) {
    printf("-1");
    return;
  }
  string ans;
  if (t == 10) {
    ans = "1" + string(n - 1, '0');
  } else {
    ans = string(n, t + '0');
  }
  printf("%s", ans.c_str());
}