Problem:
Score : 300 points

Problem Statement

Takahashi loves the number 7 and multiples of K.

Where is the first occurrence of a multiple of K in the sequence 7,77,777,\ldots? (Also see Output and Sample Input/Output below.)

If the sequence contains no multiples of K, print -1 instead.

Constraints

1 \leq K \leq 10^6

K is an integer.

Input

Input is given from Standard Input in the following format:

K

Output

Print an integer representing the position of the first occurrence of a multiple of K. (For example, if the first occurrence is the fourth element of the sequence, print 4.)

Sample Input 1

101

Sample Output 1

4

None of 7, 77, and 777 is a multiple of 101, but 7777 is.

Sample Input 2

2

Sample Output 2

-1

All elements in the sequence are odd numbers; there are no multiples of 2.

Sample Input 3

999983

Sample Output 3

999982

Solution in Python (3.8.2) (judge verdict: Wrong Answer)

#code
k=int(input())
a=7
prev=11
m=1e6
i=0
ans=0 
f=0
p=-1
z=0
for i in range (0,1000,1):
    if i==0:
        if a%k==0:
            ans=i+1
            f=1
            break
    else:
        z=pow(10,i)+prev
        print(z)
        n=7*z
        
        if n%k==0:
            ans=i+1
            f=1
            break
        else:
            prev=z

if f==0:
    print(p)
else:
    print(ans)