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:
l = list(map(int, input().split(' ')))
if l[0] == 1:
    if l[1] == 10:
        print(-1)
    else:
        print(l[1])
elif l[0] == 2:
    if l[1] == 1 or l[1] == 2 or l[1] == 3 or l[1] == 4 or l[1] == 6:
        print(12)
    elif l[1] == 7:
        print(14)
    elif l[1] == 8:
        print(16)
    elif l[1] == 5:
        print(10)
    elif l[1] == 9:
        print(18)
    else:
        print(10)
else:
    num = pow(10, l[0] - 1)
    while num % l[1] != 0:
        num += 1
    print(num)