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:
input=raw_input()
input=input.split()
n=int(input[0])
t=int(input[1])
if n==1 and t>=10:
    print'-1'
    quit()
i=1
s=1

while i<n:
    s=s*10
    i=i+1
i=0
while i<=t:
    s=s+1
    if s%t == 0:
        print s
        quit()
    i=i+1
print '-1'