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:
temp = raw_input()
n_t = temp.split(' ')
n = int(n_t[0])
t = int(n_t[1])
num = 1
sen = True
for i in range(1, n):
    num *= 10
if n == 1 and t == 10:
    pass
else:
    for i in range(num, num+2*t+1):
        if i % t ==0:
            print i
            sen = False
            break
if sen:
    print(-1)