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:
import math

def numDigits(num):
    return math.floor(math.log10(num)) + 1
    
def solve():
    n, t = [int(x) for x in input().split()]
    range_min = "1" + "0"*(n-1)
    range_max = "9"*n
    for num in range(int(range_min), int(range_max) + 1):
        if numDigits(num) == n and num % t == 0:
            print(num)
            return
    print(-1)
    return

solve()