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 findDivisible(len,div):
    if len == 1:
        if div not in list(range(10)):
            return -1
    numLen = "1"
    startNum = 1
    num = 0
    for i in range(1,len):
        numLen+="0"
    numLen = int(numLen)

    while numLen < (numLen*10):
        if int(numLen) % int(div) == 0:
            return numLen
        numLen+=1
    return -1

items = input().split()
print(findDivisible(int(items[0]),int(items[1])))