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 PYTHON):

Solution:
#!/usr/bin/env python
#n[1, 100] t[2, 10]
if __name__ == '__main__':
    n, t = map(int, raw_input().strip().split())
    #k*t in [10^(n - 1), 10^n - 1]
    a = 10**(n - 1)
    b = 10**n - 1
    k = a/t
    ans = k*t
    if ans < a:
        ans += t
    if ans <= b:
        print ans
    else:
        print -1