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
l=list(map(int,input().split(' ')))
n=l[0]
t=l[1]
d=1
n-=1
if n==0:
    for i in range(9):
        if (i+1)%t==0:
            print(i+1)
            sys.exit()
while n:
    d*=10
    n-=1
p=d*10
while d<p:
    if d%t==0:
        print(d)
        sys.exit()
    else:
        d+=1
print('-1')