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:
# 584A
# θ(n) time and space

__author__ = 'artyom'


# SOLUTION

def main():
    n, t = read(3)
    if t == 10:
        if n == 1:
            return -1
        return '1' * (n - 1) + '0'
    return str(t) * n


# HELPERS


def read(mode=2, size=None):
    # 0: String
    # 1: Integer
    # 2: List of strings
    # 3: List of integers
    # 4: Matrix of integers
    if mode == 0: return input().strip()
    if mode == 1: return input().strip().split()
    if mode == 2: return int(input().strip())
    if mode == 3: return list(map(int, input().strip().split()))
    a = []
    for _ in range(size):
        a.append(read(3))
    return a


def write(s="\n"):
    if s is None: s = ''
    if isinstance(s, tuple) or isinstance(s, list): s = ' '.join(map(str, s))
    s = str(s)
    print(s, end="\n")


res = main()
write(res)