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:
n,t=map(int,input().split())

arr = [1]*n
ans = 0
if t == 10:
    if n == 1:
        ans = -1
    else:
        arr[n-1] = 0
        for i in arr:
            ans = ans*10 + i
else:
    for i in arr:
        ans = ans*10 + i*t

print(ans)

# n -= 1
# for i in range(n):
#     for j in range(1,10):
#         x = j*10 + ans
#         if(x%t==0):
#             ans = x
#             break
# print(ans)