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())
if (N == 1 and T == 10):
    print(-1)
elif (N == 1):
    print(T)
else:
    ans = ""
    vl = 0
    for i in range(N - 1):
        ans += "1"
        vl = vl * 10 + 1
    vl = vl * 10
    val = (T - vl) % T
    if (val < 0):
        val += T
    print(ans + str(val))