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:
from math import *
n,t = input("").split(" ")
n=int(n)
t=int(t)
ll=1
ul=9
if n==1:
    ll=1
    ul=9
else:
    ll="1"
    ul="9"
    for i in range(n-1):
        ll=ll+"0"
        ul=ul+"9"
ll = int(ll)
ul=int(ul)
k=False
for i in range(ll,ul+1):
    if i%t==0:
        print(i)
        k=True
        break
if k==False:
    print(-1)