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)

t = int(input())
c = 1
N = 7
f=0
def isPrime(n): 
    if (n <= 1): 
        return False
    for i in range(2, n): 
        if (n % i == 0): 
            return False  
    return True

if isPrime(t): 
    print (-1) 
else: 
    while(N%t !=0):
        c +=1
        N = N*10 + 7
        if(len(str(N))>100):
            print(-1)
            f=1
            break
    if(f!=1):
        print(c)