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 PYTHON3):

Solution:
import sys
n, t = map(int, sys.stdin.readline().split())
if n == 1:
  if t == 10:
    print(-1)
  else:
    print(t)
else:
  rem = 1
  for i in range(n-1):
    rem = (10*rem)%t
  if rem == 0:
    print('1'+'0'*(n-1))
  else:
    print('1'+'0'*(n-2)+str(t-rem))