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:
inp = map(int, raw_input().split())
li_inp = list(inp)
n, t = li_inp[0], li_inp[1]
if ( (n >= 1 and n <= 100) and (t >= 2 and t <= 10) ):
    if (n == 1 and t == 10):
        print "-1"
    else:
        a = "1"
        st = str()
        if ( t == 10 ):
            for i in range(n-1):
                st += a
            print int(st) * t
        else:
            for i in range(n):
                st += a
            print int(st) * t