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-----
101

-----Sample Output-----
4

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

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