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:
#This is basic python file
#print "Hello Vedhika Fan!!!"
#print ""
#
s = raw_input()
dummy = s.split()
a = int(dummy[0])
b = int(dummy[1])
a = a-1
c = 10**a
d = c%b
answer = c+(b-d)
if(answer<(10**(a+1))):
    print c+(b-d)
else:
    print -1