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:
n , t = map(int , input().split(" "))

tens = int('1' + (n -1) * '0')

if (n == 1) and t in range(10) :
    print(t) 
elif t > tens :
    print(-1)
else :
    print(tens + (t - (tens % t)))

"""
def getrange(n) :
    return (10 ** (n -1) , 10 ** n)

def isdivisible(n , t) :
        limit1 , limit2 = getrange(n)
        div = [i for i in range(limit1 , limit2) if i % t == 0]
        if len(div) > 0 :
            return div[0]
        return -1

print(isdivisible(n , t))

"""