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().strip().split())
if n > 1:
    start = int(''.join(str(e) for e in [9] * (n - 1))) + 1
    while start % t != 0 and len(str(start)) == n:
        start += 1
        
    if len(str(start)) > n:
        print(-1)
    else:
        print(start)
else:
    print(t if len(str(t)) == n else -1)