import sys, re

from collections import deque, defaultdict, Counter

from math import ceil, sqrt, hypot, factorial, pi, sin, cos, radians, gcd

from itertools import accumulate, permutations, combinations, product, groupby, combinations_with_replacement

from operator import itemgetter, mul

from copy import deepcopy

from string import ascii_lowercase, ascii_uppercase, digits

from bisect import bisect, bisect_left

from heapq import heappush, heappop

from functools import reduce

def input(): return sys.stdin.readline().strip()

def INT(): return int(eval(input()))

def MAP(): return list(map(int, input().split()))

def LIST(): return list(map(int, input().split()))

def ZIP(n): return list(zip(*(MAP() for _ in range(n))))

sys.setrecursionlimit(10 ** 9)

INF = float('inf')

mod = 10 ** 9 + 7



K = INT()



tmp = 7

ans = 1

p = 1

mo = tmp%K

checked = [0]*(10**6+1)

checked[mo] = 1

while mo != 0:

    mo = mo + 7*pow(10, p, K)

    mo %= K

    p += 1

    if checked[mo]:

        print((-1))

        break

    checked[mo] = 1

else:

    print(p)

import sys, re

from collections import deque, defaultdict, Counter

from math import ceil, sqrt, hypot, factorial, pi, sin, cos, radians, gcd

from itertools import accumulate, permutations, combinations, product, groupby, combinations_with_replacement

from operator import itemgetter, mul

from copy import deepcopy

from string import ascii_lowercase, ascii_uppercase, digits

from bisect import bisect, bisect_left

from heapq import heappush, heappop

from functools import reduce

def input(): return sys.stdin.readline().strip()

def INT(): return int(eval(input()))

def MAP(): return list(map(int, input().split()))

def LIST(): return list(map(int, input().split()))

def ZIP(n): return list(zip(*(MAP() for _ in range(n))))

sys.setrecursionlimit(10 ** 9)

INF = float('inf')

mod = 10 ** 9 + 7



K = INT()



tmp = 7

ans = 1

p = 1

mo = tmp%K

checked = [0]*K

checked[mo] = 1

while mo != 0:

    mo = 10*mo + 7

    mo %= K

    p += 1

    if checked[mo]:

        print((-1))

        break

    checked[mo] = 1

else:

    print(p)

import sys, re
from collections import deque, defaultdict, Counter
from math import ceil, sqrt, hypot, factorial, pi, sin, cos, radians, gcd
from itertools import (
    accumulate,
    permutations,
    combinations,
    product,
    groupby,
    combinations_with_replacement,
)
from operator import itemgetter, mul
from copy import deepcopy
from string import ascii_lowercase, ascii_uppercase, digits
from bisect import bisect, bisect_left
from heapq import heappush, heappop
from functools import reduce


def input():
    return sys.stdin.readline().strip()


def INT():
    return int(eval(input()))


def MAP():
    return list(map(int, input().split()))


def LIST():
    return list(map(int, input().split()))


def ZIP(n):
    return list(zip(*(MAP() for _ in range(n))))


sys.setrecursionlimit(10**9)
INF = float("inf")
mod = 10**9 + 7
K = INT()
tmp = 7
ans = 1
p = 1
mo = tmp % K
checked = [0] * (10**6 + 1)
checked[mo] = 1
while mo != 0:
    mo = mo + 7 * pow(10, p, K)
    mo %= K
    p += 1
    if checked[mo]:
        print((-1))
        break
    checked[mo] = 1
else:
    print(p)

import sys, re
from collections import deque, defaultdict, Counter
from math import ceil, sqrt, hypot, factorial, pi, sin, cos, radians, gcd
from itertools import (
    accumulate,
    permutations,
    combinations,
    product,
    groupby,
    combinations_with_replacement,
)
from operator import itemgetter, mul
from copy import deepcopy
from string import ascii_lowercase, ascii_uppercase, digits
from bisect import bisect, bisect_left
from heapq import heappush, heappop
from functools import reduce


def input():
    return sys.stdin.readline().strip()


def INT():
    return int(eval(input()))


def MAP():
    return list(map(int, input().split()))


def LIST():
    return list(map(int, input().split()))


def ZIP(n):
    return list(zip(*(MAP() for _ in range(n))))


sys.setrecursionlimit(10**9)
INF = float("inf")
mod = 10**9 + 7
K = INT()
tmp = 7
ans = 1
p = 1
mo = tmp % K
checked = [0] * K
checked[mo] = 1
while mo != 0:
    mo = 10 * mo + 7
    mo %= K
    p += 1
    if checked[mo]:
        print((-1))
        break
    checked[mo] = 1
else:
    print(p)

-checked = [0] * (10**6 + 1) +checked = [0] * K -    mo = mo + 7 * pow(10, p, K) +    mo = 10 * mo + 7