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 = [int(x) for x in input().split(' ')]
t = n[1]
n = n[0]
try:
    start, stop = int('9'*(n-1))+1, int('9'*n)
except ValueError:
    start = 1
    stop = int('9'*n)
for i in range(start, stop+1):
    if i % t == 0:
        print(i)
        exit(0)
print(-1)