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, input().split())

min = '1'
for i in range(n - 1): min += '0'
min = int(min)

start = max(min // t, 1)
cur = start * t
while len(str(cur)) <= n:
    if len(str(cur)) == n:
        print(cur)
        sys.exit(0)
    
    cur *= t
print(-1)