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:
#!/usr/bin/python3

n, t = map(int, input().split())

if n == 1 and t < 10:
    print(t)
    exit(0)

l, r = 1, 10 ** n // t + 179
while l < r - 1:
    mid = (l + r) // 2
    if len(str(t * mid)) < n:
        l = mid
    else:
        r = mid

if len(str(r * t)) != n:
    print(-1)
else:
    print(r * t)