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:
string = '1'
substring = '1'
n , t = map(int,input().split())
for i in range (n):
    string += '0'
for i in range (n-1):
    substring += '0'

value = 0
for i in range (int(substring),int(string)):
    if i%t == 0:
        value = i
        break

if value == 0 :
    print(-1)
else:
    print(value)