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 = [int(a) for a in input().split()]

# number = [0] * n
# if n == 1 and len(str(t)) == 1:
#     print(t)
# else:
if n == 1 and t == 10:
    print(-1)
elif t == 10:
    print(t*10**(n-2))
else:
    print(t*10**(n-1))
#     if t == 2:
#         number[-1] = 2
#         for x in range(n-1):
#             number[x] == 1
#     elif t == 3:
#         number[0] = 1
#         number[1] = 2
#         for x in range(2, number):
#             number[x] = 0
#     elif t == 4:
#         number[-2], number[-1] = 1, 2
#         for x in range(n-2):
#             number[x] = 1
#     elif t == 5:
#         number[-1] = 5
#         for x in range(n-1):
#             number[x]=1
#     elif t == 6:
#         number[0] = 1
#         number[1] = 2
#         for x in range(2, number):
#             number[x] = 0
#     elif t == 7: