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:
from sys import stdin
n, t = list(map(int, stdin.readline().rstrip().split(' ')))
cur = t

temp = t
digits = 0
while temp > 0:
    temp //= 10
    digits += 1

if digits > n:
    print(-1)
    exit()
    
while True:
    temp = cur
    digits = 0
    while temp > 0:
        temp //= 10
        digits += 1
    
    if digits == n:
        print(cur)
        exit()
    cur *= t