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:
n,t = (int(item) for item in input().split())
l = [1,2,3,4,5,6,7,8,9]
num = 0
for i in range(1,n+1):
    num *= 10
    if i == n: num += 0
    else: num += i
if num == 0:
    for i in l:
        if i%t == 0:
            num = i
            break
        elif i == 9:
            num = -1
else:
    while num%t != 0:
        num += 1
print(num)