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:
x, y = map(int, input().split())

min = [1]
max = [9]

for i in  range(1,x):
    min.append(0)
    max.append(9)

str1 = ""
for ele in min:
    str1 += str(ele)
min = int(str1)

str1 = ""
for ele in max:
    str1 += str(ele)
max = int(str1)

flag = 0

for j in range(min,max+1):
    if j % y == 0:
        print(j)
        flag = 1
        break

if flag == 0:
    print(-1)