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 PYTHON):

Solution:
a,b = map(int, raw_input().split())
x = str(b)
A = []
if a == 1 and b == 10:
    print -1
else:
    for i in x:
        A.append(i)
    while len(A)<a:
        A.append(0)
    S = str(A[0])
    for k in range(1,len(A)):
        S = S + str(A[k])
    print S