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 sys
import io

def run(test,res):
    x = io.StringIO()
    with io.StringIO(test) as sys.stdin:
        with x as sys.stdout:
            work()
            z = x.getvalue().strip()
    sys.stdout = sys.__stdout__
    print(z == test)
    print(res)
    print(z)

def work():
    n,t = map(int, input().split())
    c = "1"+"".join(["0"]*(n-1))
    r = t*(1 + int(c)//t)
    if (len(str(r)) != n):
        r = -1
    print(r)


def test():
    run("""3 2""", "102")
    run("""1 9""", "9")
    run("""1 10""", "-1")

if len(sys.argv) > 1:
    test()
else:
    work()