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:
def power(a, b):
    if b == 0:
        return 1
    elif b % 2 == 0:
        a_1 = a * a
        return pow(a_1, b // 2)
    return a * pow(a, b - 1)


def ol_rd(n, t):
    z = power(10, n - 1)
    while z % t != 0 and z + 1 < power(10, n):
        z += 1
    if z % t == 0:
        return z
    return -1


N, T = [int(i) for i in input().split()]
print(ol_rd(N, T))