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:
from sys import stdin, stdout
n, t = 0, 0
line = ''

def solve():
    if t == 10 and n == 1:
        print -1
        return

    if t < 10:
        nums = [t] + [0] * (n-1)
    else:
        nums = [t] + [0] * (n-2)
    print ''.join(map(str, nums))

while True:
    line = stdin.readline()
    if not line: break
    n, t = map(int, line.split())
    solve()