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:
if __name__ == '__main__':
    x = raw_input()
    x = x.split(" ")
    n = int(x[0])
    t = int(x[-1])
	
    s = ''
    if t == 10:
	if n > 1:
	    for i in range(1, n):
	        s += '1' 
	    s += '0'
        else:
	    s = -1
    else:
	for i in range(n):
	    s += chr(t + 48)
    print s