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:

a , b = input().split()

a = int(a)
b = int(b)
c = b
if a == 1 and b <= 9:
    print(b)
elif a == 1 and b > 9:
    print(-1)
elif a == len(str(b)):
    print(b)
else:
    for i in range(a):
        c = c * 10
        #print(c)
        if len(str(c)) == a:
            print(c)
            exit()