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
#x = [int(x) for x in input().split()] 
#joined_string = ' '.join([str(v) for v in output])
#print(joined_string)
#n,m,a = map(int,input().split())
#for taking matrix input:
#for i in range(n):
#   a.append([int(x) for x in input().split()])
#alphabet = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']
a,b = map(int,input().split())
n = '1'
for i in range(a-1):
    n += '0'



d = len(n)-len(str(b))

num = '1'
for i in range(d):
    num += '0'
c = b * int(num)
if int(d) < 0:
    print(-1)
elif int(d) == 0:
    print(b)
else:
    print(c)