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:
n,t = map(int,input().split())
a = []
if t!=10:
     for i in range(n):
          a.append(t)
     ans = [str(k) for k in a]
     print(''.join(ans))
elif n!=1:
     a.append(1)
     for i in range(n-1):
          a.append(0)
     ans = [str(k) for k in a]
     print(''.join(ans))
else:
     print(-1)