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:
import math
n,k=map(int,input().split())
res = []
res.append('1')
for i in range(n - 1):
    res.append('0')
m = ""
for i in res:
    m += i
m = int(m)
r = m * k
r = str(r)
if len(r) == n:
    print(r)
elif len(r)>n:
    while len(r)!=n:
        r=int(r)-k
        r=str(r)
    if r=='0':
        print(-1)
    else:
        print(r)
elif len(r)<n:
    while len(r)!=n:
        r=int(r)-k
        r=str(r)
    print(r)