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 (Python):
def main(sample_file = ''):

    """ convenient functions
    
    
    
    
    
    """

    """convenient decorator
    
    
        
        
        
        
        
        
        
        
        
        
    """
    
    
    import sys
    sys.setrecursionlimit(10**7)
    from itertools import accumulate, combinations, permutations, product 
    
    from math import factorial, ceil, floor, sqrt
    def factorize(n):
        """return the factors of the Arg and count of each factor
        
        Args:
            n (long): number to be resolved into factors
        
        Returns:
            list of tuples: factorize(220) returns [(2, 2), (5, 1), (11, 1)]
        """
        fct = []  
        b, e = 2, 0  
        while b * b <= n:
            while n % b == 0:
                n = n // b
                e = e + 1
            if e > 0:
                fct.append((b, e))
            b, e = b + 1, 0
        if n > 1:
            fct.append((n, 1))
        return fct
    def combinations_count(n, r):   
        """Return the number of selecting r pieces of items from n kinds of items.
        
        Args:
            n (long): number
            r (long): number
        
        Raises:
            Exception: not defined when n or r is negative
        
        Returns:
            long: number
        """
        
        if n < 0 or r < 0:
            raise Exception('combinations_count(n, r) not defined when n or r is negative')
        if n - r < r: r = n - r
        if r < 0: return 0
        if r == 0: return 1
        if r == 1: return n
        numerator = [n - r + k + 1 for k in range(r)]
        denominator = [k + 1 for k in range(r)]
        for p in range(2,r+1):
            pivot = denominator[p - 1]
            if pivot > 1:
                offset = (n - r) % p
                for k in range(p-1,r,p):
                    numerator[k - offset] /= pivot
                    denominator[k] /= pivot
        result = 1
        for k in range(r):
            if numerator[k] > 1:
                result *= int(numerator[k])
        return result
    def combinations_with_replacement_count(n, r):
        """Return the number of selecting r pieces of items from n kinds of items allowing individual elements to be repeated more than once.
        
        Args:
            n (long): number
            r (long): number
        
        Raises:
            Exception: not defined when n or r is negative
        
        Returns:
            long: number
        """
        if n < 0 or r < 0:
            raise Exception('combinations_with_replacement_count(n, r) not defined when n or r is negative')
        elif n == 0:
            return 1
        else:
            return combinations_count(n + r - 1, r)
    from bisect import bisect_left, bisect_right
    from collections import deque, Counter, defaultdict 
    from heapq import heapify, heappop, heappush, heappushpop, heapreplace,nlargest,nsmallest 
    from copy import deepcopy, copy 
    import operator
    from operator import itemgetter 
    
    
    from functools import reduce, lru_cache
    def chmin(x, y):
        """change minimum
        if x > y, x = y and return (x, True).
        convenient when solving problems of dp[i]
        
        Args:
            x (long): current minimum value
            y (long): potential minimum value
        
        Returns:
            (x, bool): (x, True) when updated, else (x, False)
        """
        if x > y:
            x = y
            return (x, True)
        else:
            return (x, False)
    def chmax(x, y):
        """change maximum
        if x < y, x = y and return (x, True).
        convenient when solving problems of dp[i]
        
        Args:
            x (long): current maximum value
            y (long): potential maximum value
        
        Returns:
            (x, bool): (x, True) when updated, else (x, False)
        """
        if x < y:
            x = y
            return (x, True)
        else:
            return (x, False)

    from fractions import gcd 
    def gcds(numbers):
        return reduce(gcd, numbers)
    def lcm(x, y):
        return (x * y) // gcd(x, y)
    def lcms(numbers):
        return reduce(lcm, numbers, 1)
    def make_divisors(n, reversed=False):
        """create list of divisors
        
        Args:
            number (int): number from which list of divisors is created
            reversed (bool, optional): ascending order if False. Defaults to False.
        
        Returns:
            list: list of divisors
        """
        divisors = set()
        for i in range(1, int(n**0.5)+1):
            if n % i == 0:
                divisors.add(i)
                divisors.add(n//i)
        return sorted(list(divisors),reverse=reversed)
    
    
    
    INF = 10 ** 18
    MOD = 10 ** 9 + 7
    AtoZ = list('abcdefghijklmnopqrsruvwxyz') 
    modpow = lambda a, n, p = MOD: pow(a, n, p) 
    def modinv(a, p = MOD):
        
        
        return modpow(a, p-2, p)
    def modinv_list(n, p = MOD):
        if n <= 1:
            return [0,1][:n+1]
        else:
            inv_t = [0,1]
            for i in range(2, n+1):
                inv_t += [inv_t[p % i] * (p - int(p / i)) % p]
            return inv_t
    def modfactorial_list(n, p = MOD):
        if n == 0:
            return [1]
        else:
            l = [0] * (n+1)
            tmp = 1
            for i in range(1, n+1):
                tmp = tmp * i % p
                l[i] = tmp
            return l
    def modcomb(n, k, fac_list = [], p = MOD):
        
        
        from math import factorial
        if n < 0 or k < 0 or n < k: return 0
        if n == 0 or k == 0: return 1
        if len(fac_list) <= n:
            a = factorial(n) % p
            b = factorial(k) % p
            c = factorial(n-k) % p
        else:
            a = fac_list[n]
            b = fac_list[k]
            c = fac_list[n-k]
        return (a * modpow(b, p-2, p) * modpow(c, p-2, p)) % p
    def modadd(a, b, p = MOD):
        return (a + b) % MOD
    def modsub(a, b, p = MOD):
        return (a - b) % p
    def modmul(a, b, p = MOD):
        return ((a % p) * (b % p)) % p
    def moddiv(a, b, p = MOD):
        return modmul(a, modpow(b, p-2, p))

    class UnionFindTree:
        """union find tree class
        TODO: fix this description...
        how to use (example):
        >>  uf = UnionFindTree(N) 
        >>  if uf.find_root(a) == uf.find_root(b):
        >>      do something
        >>  else:
        >>      do something
        >>      uf.unite(a, b)
        """
        def __init__(self, N):
            self.root = [-1] * (N+1)
            self.rank   = [0]  * (N+1)
            self.connected_num = [1] * (N+1)
    
        def find_root(self,x):
            root = self.root
            while root[x] != -1:
                x = root[x]
            return x
    
        def unite(self,x,y):
            root = self.root
            rank = self.rank
            connected_num = self.connected_num
            find_root = self.find_root
    
            rx = find_root(x)
            ry = find_root(y)
            if rx != ry:
                if rank[rx] < rank[ry]:
                    root[rx] = ry
                    rx,ry = ry,rx
                else:
                    if rank[rx] == rank[ry]:
                        rank[rx] += 1
                    root[ry] = rx       
                connected_num[rx] += connected_num[ry]

    class SegTree:
        """
        ref: https://qiita.com/takayg1/items/c811bd07c21923d7ec69
        init(init_val, ide_ele): 配列init_valで初期化 O(N)
        update(k, x): k番目の値をxに更新 O(logN)
        query(l, r): 区間[l, r)をsegfuncしたものを返す O(logN)
        """
        def __init__(self, init_val, segfunc, ide_ele):
            """
            init_val: 配列の初期値
            segfunc: 区間にしたい操作
            ide_ele: 単位元
            n: 要素数
            num: n以上の最小の2のべき乗
            tree: セグメント木(1-index)
            """
            n = len(init_val)
            self.segfunc = segfunc
            self.ide_ele = ide_ele
            self.num = 1 << (n - 1).bit_length()
            self.tree = [ide_ele] * 2 * self.num
            
            for i in range(n):
                self.tree[self.num + i] = init_val[i]
            
            for i in range(self.num - 1, 0, -1):
                self.tree[i] = self.segfunc(self.tree[2 * i], self.tree[2 * i + 1])

        def update(self, k, x):
            """
            k番目の値をxに更新
            k: index(0-index)
            x: update value
            """
            k += self.num
            self.tree[k] = x
            while k > 1:
                self.tree[k >> 1] = self.segfunc(self.tree[k], self.tree[k ^ 1])
                k >>= 1

        def query(self, l, r):
            """
            [l, r)のsegfuncしたものを得る
            l: index(0-index)
            r: index(0-index)
            """
            res = self.ide_ele
            l += self.num
            r += self.num
            while l < r:
                if l & 1:
                    res = self.segfunc(res, self.tree[l])
                    l += 1
                if r & 1:
                    res = self.segfunc(res, self.tree[r - 1])
                l >>= 1
                r >>= 1
            return res

    
    
    
    
    
    
    
    

    def BellmanFord(N, M, ABC, vertex_start, vertex_end, value_if_inf = -1, find_shortest = False):
        """to calculate furthest or shortest length between vertex_start and vertex_end using BellmanFord algorithm
        
        Args:
            N (int): number of vertices
            M (int): number of edges
            ABC (list): [(ai, bi, ci) for _ in range(N)] where i-th edge is directed from vertex ai to vertex bi and the length is ci 
            vertex_start (int): start vertex. usually use 0.
            vertex_end (int): end vertex. usually use N-1.
            value_if_inf (int or string as you like, optional): value you want when the furthest (or shortest) distance is infinite (or -infinite). Defaults to -1.
            find_shortest (bool, optional): choose False to find furthest path. Defaults to False.
        
        Returns:
            int or string: normally int (but can be str if you set value_if_inf to str)
            
        Example:
                N, M, P = R()
                ABC = [R() for _ in range(M)]
                ABC = [(a-1, b-1, c-P) for a, b, c in ABC]
                print(BellmanFord(N, M, ABC, 0, N-1, value_if_inf = 'inf'))

        """

        def make_reachable_list(N, M, ABC, vertex_start, vertex_end):
            reachable_to_direct = defaultdict(list)
            reachable_from_direct = defaultdict(list)
            reachable_from_start = [False] * N
            reachable_to_end = [False] * N
            reachable_from_start[vertex_start] = True
            reachable_to_end[vertex_end] = True
            reachable_from_both_sides = [False] * N
            dfs_from_start = []
            dfs_to_end = []
            for a, b, c in ABC:
                reachable_to_direct[a].append(b)
                reachable_from_direct[b].append(a)
                if a == vertex_start:
                    dfs_from_start.append(b)
                    reachable_from_start[b] = True
                if b == vertex_end:
                    dfs_to_end.append(a)
                    reachable_to_end[a] = True
            while dfs_from_start:
                v = dfs_from_start.pop()
                for i in reachable_to_direct[v]:
                    if not reachable_from_start[i]:
                        reachable_from_start[i] = True
                        dfs_from_start.append(i)
            while dfs_to_end:
                v = dfs_to_end.pop()
                for i in reachable_from_direct[v]:
                    if not reachable_to_end[i]:
                        reachable_to_end[i] = True
                        dfs_to_end.append(i)
            for i in range(N):
                reachable_from_both_sides[i] = reachable_from_start[i] and reachable_to_end[i]
            return reachable_from_both_sides
        
        reachable_from_both_sides = make_reachable_list(N, M, ABC, vertex_start, vertex_end)
        
        if find_shortest:
            dist = [INF for i in range(N)]
        else:
            dist = [-INF for i in range(N)]
        
        dist[vertex_start] = 0
        for i in range(N):
            updated = False
            for a, b, c in ABC:
                if not reachable_from_both_sides[a]:
                    continue
                elif find_shortest:
                    update_condition = dist[a] + c < dist[b]
                else:
                    update_condition = dist[a] + c > dist[b]
                if dist[a] != INF and update_condition:
                    dist[b] = dist[a] + c
                    updated = True
                    if i == N-1:
                        return value_if_inf
            if not updated:
                break
        return dist[vertex_end]

    
    def warshall_floyd(number_vertex, XYD, shift_one_for_vertex=False):
        
        
        
        
        
        d = [[float("inf")]*number_vertex for i in range(number_vertex)]
        for x, y, dist in XYD:
            if shift_one_for_vertex:
                x = x - 1
                y = y - 1
            d[x][y] = dist
            d[y][x] = dist
        for i in range(number_vertex):
            d[i][i] = 0 
        for k in range(number_vertex):
            for i in range(number_vertex):
                for j in range(number_vertex):
                    d[i][j] = min(d[i][j],d[i][k] + d[k][j])
        return d


    """ initialize variables and set inputs
    
        
        
            
            
    
        
        
        
        
        
        
        
    
        
        
        
        
    
        
        
    """

    
    r = lambda: sys.stdin.readline().strip()
    r_int = lambda: int(r())
    r_float = lambda: float(r())
    R = lambda: list(map(int, r().split()))
    R_str = lambda: r().split()
    R_map = lambda: map(int, r().split())
    R_float = lambda: list(map(float, r().split()))
    R_tuple = lambda: tuple(map(int, r().split()))

    """ how to treat input
    
    
    
    
    
    
    
    """

    
    if sample_file:
        sys.stdin = open(sample_file)
        
    
    
    

    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    K = r_int()
    ans = 1
    tmp = 7
    for i in range(10**7):
        if tmp % K == 0:
            print(ans)
            return
        else:
            tmp = (tmp % K) * 10 + 7
            ans += 1
    print(-1)
    

    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    

    
    
    
    
    
    
    
    
    
    
    
    
    
    

    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    

    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    

    


    
    
    

    """memo: how to use defaultdict of list
    
    Dic = defaultdict(list)
    
    Dic[x].append(y)
    
    for k, v in Dic.items():
    """
    
    """memo: how to solve binary problems
    
    >>> a = 5
    >>> bin_str_a = format(a, '
    >>> print(bin_str_a)
    0b0101 
    """
    
    """memo: how to solve the problem
    creating simple test/answer
    greed
    simple dp
    graph
    """

if __name__ == '__main__':
    main()

Solution (Python):
def main():
    K = int(input())
    if K % 2 == 0 or K % 5 == 0:
        print(-1)
        return
    cnt = 1
    tmp = 7
    while tmp % K != 0:
        tmp = tmp * 10 + 7
        tmp %= K
        cnt += 1

    print(cnt)

main()

Solution (Python):
n = int(input())
ok  = 0
s = 0
ans = -1
mex = 10**7
for i in range(1,mex):
    s= (s*10)+7
    s = s%n
    if s==0:
        ans = i
        break
print(ans)

Solution (Python):
import sys
K = int(input())

power = 7
SUM = 0

for i in range(1, 10 ** 6):
    SUM += power
    if SUM % K == 0:
        print(i)
        sys.exit()
    power *= 10
    power %= K

print(-1)

Solution (Python):
k = int(input())
if k % 2 == 0:
    print(-1)
    exit()

ten = 1
now = 0
for i in range(10**8):
    x = (ten*7)%k
    now = (now+x)%k
    if now == 0:
        print(i+1)
        exit()
    ten = ten*10%k
print(-1)

Solution (Python):
k=int(input())
temp=7
for i in range(1,k+1):
    if temp%k==0:
        print(i)
        break
    temp=(temp*10+7)%k
else:
    print(-1)

Solution (Python):
k = int(input())
cnt = 1
mods = set()
mod = 7
while True:
  mod = mod%k
  if mod==0:
    break
  if mod not in mods:
    mods.add(mod)
    cnt += 1
  else:
    cnt = -1
    break
  mod = (10*mod)+7
print(cnt)

Solution (Python):
import math
x = int(input())
rem = 7 % x
cnt = 1
while rem != 0 and cnt <= 1000000:
	rem = (10 * rem + 7) % x
	cnt += 1
if rem == 0:
	print(cnt)
else:
	print(-1)

Solution (Python):


k=int(input())
ans=0
flag=True
for i in range(0,10**6+1):
  ans= ((ans%k)*(10%k))%k+7%k
  ans=ans%k
  if ans==0:
    print(i+1)
    flag=False
    break
if flag:
  print(-1)

Solution (Python):
import sys
K=int(input())
rest = 7 % K
if rest == 0:
  print(1)
  sys.exit()
for i in range(2,K+5): 
  rest = (rest*10+7) % K
  if rest == 0:
    print(i)
    sys.exit()
else:
  print(-1)

Solution (Python):
import sys
n = int(input())

if n % 2 == 0 or n % 5 == 0:
  print(-1)
  sys.exit()
  
tmp = 7

count = 1
while True:
  if tmp % n == 0:
    print(count)
    sys.exit()

  count += 1
  tmp = tmp * 10 + 7
  tmp %= n

Solution (Python):
K = int(input())
if K % 2 == 0:
    print(-1)
else:
    r = 0
    rem = 7
    while (True):
        r += 1
        rem = rem % K
        if rem == 0:
            break
        if r > K:
            r = -1
            break
        rem = (rem * 10) + 7
    print(r)

Solution (Python):
from sys import stdin
input = stdin.readline


def main():
  K = int(input())

  if 7 % K == 0:
    print(1)
    return
  if K % 2 == 0:
    print(-1)
    return
  dp = [0]*(10**7)
  const = 7 % K
  dp[0] = const
  ten = 1
  for i in range(1, 10**7):
    ten = ten*10 % K
    new = (7*ten) % K
    dp[i] = (new + dp[i-1]) % K
    if dp[i] % K == 0:
      print(i+1)
      
      return

  print(-1)


if(__name__ == '__main__'):
  main()

Solution (Python):
k = int(input())
d = 0
t = 0
l = [0] * k
l[0] = 1 % k
for i in range(1, k):
  l[i] = (l[i-1] * 10) % k
for i in range(k):
  t = t + 7 * l[i]
  if t % k == 0:
    print(i + 1)
    exit()
  else:
    t = t % k
print(-1)

Solution (Python):
k=int(input())

x=7
if k%2==0 or k%5==0:
    print(-1)
    exit()
for i in range(k):
    y=x%k
    
    if y==0:
        print(i+1)
        exit()
    x=10*y+7

Solution (Python):
n = int(input())
x = 7
for i in range(1000000):
    x %= n
    if x==0:
        print(i+1)
        break
    x = x * 10 + 7
else:
    print(-1)

Solution (Python):
K = int(input())
if K % 2 == 0 or K % 5 == 0:
    print(-1)
else:
    tmp, i, p = 0, 1, 0
    while True:
        p = (p * 10 + 7) % K
        if not p:
            print(i)
            break
        i += 1

Solution (Python):
(K,) = [int(x) for x in input().split()]
ans = 0
seven = 7
for i in range(1000000):
    if seven % K == 0:
        print(i + 1)
        break
    seven = (10 * seven + 7) % K
else:
    print(-1)

Solution (Python):
K=int(input())
if K%2==0:
    print(-1)
    exit()
elif K==7:
    print(1)
    exit()
i=0
mod=0
while(i<K):
    mod=(mod+7*pow(10,i,K))%K
    if mod==0:
        print(i+1)
        exit()
    i+=1
print(-1)

Solution (Python):
K = int(input())

if 7%K==0:
    print(1)
else:
    ans = 1
    b = 7%K
    while ans < 10**7+1000:
        b = (b*10+7)%K
        if b == 0:
            print(ans+1)
            break
        else:
            ans += 1
    else:
        print(-1)

Solution (Python):
K = int(input())

if K % 2 == 0 or K % 5 == 0:
	print(-1)
else:
	n = 1
	m = 0
	d = 7
	while True:
		m = (m + d) % K
		if m == 0:
			break
		if d == 0:
			n = -1
			break
		n += 1
		d = (d * 10) % K
	print(n)

Solution (Python):
k = int(input())

mod = 0
for i in range(k):
    mod = (mod * 10 + 7) % k
    if mod == 0:
        print(i + 1)
        exit(0)

print(-1)

Solution (Python):
def main():
    K=int(input())
    x=7
    for i in range(1,10**8):
        m=x%K
        
        if m==0:
            print(i)
            break
        x=m*10+7
        
    else:
        print(-1)

if __name__ == '__main__':
    main()

Solution (Python):

import sys

sysread = sys.stdin.buffer.readline
read = sys.stdin.buffer.read


sys.setrecursionlimit(10**7)







INF = 1 << 50



def run():
    K = int(input())
    left = 7 % K
    right = 1 % K
    next_add = 1
    if not K % 2:
        print(-1)
        return None
    ans = 1
    right_set = set()
    while True:
        if not left * right % K:
            print(ans)
            return None
        else:
            right_set.add(right)
            next_add = next_add * 10 % K
            right = (right + next_add) % K
            ans += 1
            if right in right_set:
                print(-1)
                return

if __name__ == "__main__":
    run()

Solution (Python):
k=int(input())
cnt=1
flag=True
if k%2==0:
    flag=False
    print(-1)
else:
    keta=10
    tmp=0
    while cnt<=10**6:
        tmp+=pow(keta,cnt-1,k)*7
        if tmp%k==0:
            print(cnt)
            flag=False
            break
        cnt+=1
if flag:
    print(-1)

Solution (Python):
K = int(input())

count = 1
num = 7
if K % 2 == 0 or K % 5 == 0:
    count = -1
else:
    while True:
        if num % K == 0:
            break
        num = (num*10 + 7) % K
        count += 1
        if count >= 10**6 * 10**5:
            count = -1
            break
print(count)

Solution (Python):
def main():
    import sys
    import time
    start=time.time()
    K=int(sys.stdin.readline())
    if K%2==0:
        print(-1)
        return

    L=[7%K]
    L2=[7%K]
    if L[0]==0:
        print(1)
        return

    idx=0
    while True:
        L2.append((L2[idx]*10)%K)
        L.append((L[idx]+L2[idx+1])%K)
        if L[-1]==0:
            print(len(L))
            return
        idx+=1

        if time.time()-start>=1.5:
            print(-1)
            return
main()

Solution (Python):
k= int(input())
flag= -1
if k%2 ==0 or k%5==0:
    print("-1")
else:
    temp=7
    for i in range(0,k+1):
        if temp%k ==0:
            flag=i
            break
        else:
            temp= (temp*10+7)% k
    if flag==-1:
        print("-1")
    else:
        print(i+1)

Solution (Python):
mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    K = int(input())
    seen = [0] * K
    d = 0
    for i in range(1, 10**6+1):
        d = (d * 10 + 7) % K
        if d == 0:
            print(i)
            exit()
        if seen[d]:
            break
        seen[d] = 1
    print(-1)


if __name__ == '__main__':
    main()

Solution (Python):
k = int(input())
ml = []
a = 7
m = 7
i = 0
while m>0:
  m = a%k
  a = 10*m+7
  i += 1
  if i>k :
    i=-1
    break
print(i)

Solution (Python):
k = int(input())
a = [0,7]
for i in range(2,10**6+1):
    x = a[i-1]*10
    x %= k
    a.append(x)
tnp = 0
for i in range(1,len(a)):
    tnp += a[i]
    tnp %= k
    if (tnp==0):
        print(i)
        exit()
print(-1)

Solution (Python):
k=int(input(""))
s=0
a=7%k
for i in range(1,k+1):
    s+=a
    s%=k
    if(s==0):
        print(i)
        break
    a=(10*a)%k
else:
    print(-1)

Solution (Python):
k = int(input())

a = 7
ans = 0

for i in range(1000000):
    if a % k == 0:
        ans = i + 1
        break
    a = (a*10 + 7) % k

if ans == 0:
    print("-1")
else:
    print(ans)

Solution (Python):
k = int(input())
a = 7 % k
ans = 1
for i in range(k):
    if a != 0:
        a = (10*a + 7) % k
        ans += 1
    else:
        print(ans)
        break
else:
    print(-1)

Solution (Python):
K = int(input())

cnt = 0
n = 7
while cnt <= K:
    cnt += 1
    if n % K == 0:
        break
    n = (10 * n + 7) % K

if cnt == K+1:
    print(-1)
else:
    print(cnt)

Solution (Python):
k = int(input())
cnt = 0
tmp = 0
while cnt < 1000000:
  tmp += 7 * pow(10, cnt, k)
  cnt += 1
  tmp %= k
  if tmp == 0:
    break
if cnt == 1000000:
  print(-1)
else:
  print(cnt)

Solution (Python):
k = int(input())

x = 7
e = 10

for i in range(10000000):
    
    if x % k == 0:
        print(i + 1)
        exit()
    x = (x * e + 7) % k

print("-1")

Solution (Python):

import sys
sys.setrecursionlimit(10**8)
def input(): return sys.stdin.readline().strip()
def INT(): return int(input())
def MAP(): return map(int, input().split())
def LIST(): return list(map(int, input().split()))
def ZIP(n): return [LIST() for _ in range(n)]
def NSTR(n): return [input() for _ in range(n)]


INF = float("inf")
MOD = 10**9 + 7


def main():
    K = input()
    if K[-1] not in "1379":
        print(-1)
        return
    K = int(K)

    count = 0
    ans = 7
    for k in range(10**6):
        ans = ans % K
        count += 1
        if ans == 0:
            print(count)
            return
        else:
            ans = ans*10+7
    print(-1)

    return


if __name__ == '__main__':
    main()

Solution (Python):


def main():
    k = int(input())
    flg = [False for _ in range(k)]
    r = 7
    cnt = 0

    while True:
        r = r % k
        cnt += 1
        if r == 0:
            break
        if flg[r]:
            cnt = -1
            break
        flg[r] = True
        r = r*10 + 7

    print(cnt)

if __name__ == '__main__':
    main()

Solution (Python):
K = int(input())
cnt = 7
prev = 7
if K == 1 or K == 7:
    print(1)
    exit()
for i in range(K):
    prev = (prev*10) % K
    cnt += prev
    if cnt % K == 0:
        print(i+2)
        exit()
else:
    print(-1)

Solution (Python):
k=int(input())

ans=0
tenmod=1

for i in range(10**8):
  if i>0:
    tenmod=tenmod*10%k
  ans=(ans+7*tenmod)%k
  
  if ans==0:
    print(i+1)
    exit()
print(-1)

Solution (Python):
K = int(input())
if K%2==0:
    print("-1")
elif K%5==0:
    print("-1")
else:
    ans = 0
    temp = 0
    check = 0
    for i in range(K):
        ans += 1
        temp *= 10
        temp += 7
        temp %= K
        
        if temp==0:
            check+=1
        
        if check==1:
            break
    print(ans)

Solution (Python):
def resolve():
    k = int(input())
    ans = 1
    ct = 0
    num = 7
    while ct <= 2*10**6:
        num %= k
        if num == 0:
            print(ans)
            exit()
        else:
            num = (num * 10 + 7)%k
            ans += 1
            ct += 1
    print(-1)
resolve()

Solution (Python):
K = int(input())
if(K%2 ==0 or K%5 == 0):
    print("-1")
    exit()
sum = 0
a = 7%K
sum += a
if(a == 0):
    print("1")
    exit()
for i in range(2, 10**8):
    sum += (a*10)%K
    sum = sum%K
    a = (a*10)%K
    if(sum == 0):
        print(i)
        exit()

Solution (Python):
K = int(input())
if (K%2==0)or(K%5==0):
  print(-1)
  
else:
  x = 7
  i = 1
  x %= K
  while (x!=0)or(i>=10**7):
    x += (7%K) * pow(10,i,K)
    x %= K
    i += 1
  if i<10**7:  
    print(i)
  else:
    print(-1)

Solution (Python):
from functools import reduce
from fractions import gcd
import math
import bisect
import itertools
import sys
input = sys.stdin.readline
INF = float("inf")



def main():
    K = int(input())

    if K % 2 == 0:
        print(-1)
        return

    tmp = 7
    ans = 1
    while tmp % K != 0:
        tmp = (tmp % K) * 10 + 7
        ans += 1
        if ans >= 10000000:
            print(-1)
            return

    print(ans)

if __name__ == '__main__':
    main()

Solution (Python):
def getN():
    return int(input())
def getNM():
    return map(int, input().split())
def getList():
    return list(map(int, input().split()))
def getArray(intn):
    return [int(input()) for i in range(intn)]
def input():
    return sys.stdin.readline().rstrip()
def rand_N(ran1, ran2):
    return random.randint(ran1, ran2)
def rand_List(ran1, ran2, rantime):
    return [random.randint(ran1, ran2) for i in range(rantime)]
def rand_ints_nodup(ran1, ran2, rantime):
  ns = []
  while len(ns) < rantime:
    n = random.randint(ran1, ran2)
    if not n in ns:
      ns.append(n)
  return sorted(ns)

def rand_query(ran1, ran2, rantime):
  r_query = []
  while len(r_query) < rantime:
    n_q = rand_ints_nodup(ran1, ran2, 2)
    if not n_q in r_query:
      r_query.append(n_q)
  return sorted(r_query)

from collections import defaultdict, deque, Counter
from sys import exit
from decimal import *
import heapq
import math
from fractions import gcd
import random
import string
import copy
from itertools import combinations, permutations, product
from operator import mul, itemgetter
from functools import reduce
from bisect import bisect_left, bisect_right

import sys
sys.setrecursionlimit(1000000000)
mod = 10 ** 9 + 7





K = getN()
if K == 1 or K == 7:
    print(1)
    exit()

prev1 = 7

cnt = 1
for i in range(10 ** 6 + 2):
    cnt += 1
    mi = (prev1 * 10 + 7) % K
    if mi == 0:
        print(cnt)
        exit()
    prev1 = mi
print(-1)

Solution (Python):
k = int(input())
cnt = 1
ans = 7
mul = 70 % k
ans %= k
flags = [False] * k
flags[ans] = True
while ans != 0:
    ans += mul
    cnt += 1
    ans %= k
    mul *= 10
    mul %= k
    if flags[ans]:
        cnt = -1
        break
    flags[ans] = True

print(cnt)

Solution (Python):
def main():
    K = int(input())
    if K in [1,7]:
        print(1)
        return
    if K == 2:
        print(-1)
        return
    
    k = 7 % K
    current = k
    count = 1
    foot_print = set()
    while True:
        count += 1
        current = (k + (current * 10)) % K
        if current == 0:
            print(count)
            return
        if current in foot_print:
            break
        foot_print.add(current)

    print(-1)
    

if __name__ == '__main__':
    main()

Solution (Python):
LI = lambda: list(map(int, input().split()))

K = int(input())


def main():
    s = 1
    p = 1
    for i in range(1, K + 1):
        if 7 * s % K == 0:
            print(i)
            return
        p = 10 * p % K
        s = (s + p) % K
    print(-1)


if __name__ == "__main__":
    main()

Solution (Python):
K = int(input())
remainder = 0
for i in range(K):
    remainder += 7*(pow(10,i,K))%K
    remainder %= K
    
    if remainder == 0:
        print(i+1)
        break
else:
    print(-1)

Solution (Python):
k = int(input())
valM = {}
count = 0
flag = 1
amari = 0
while True:
    count+=1
    amari = (amari*10+7)%k
    if (amari in valM):
        break
    if amari == 0:
        print(count)
        flag = 0
        break
    else:
        valM[amari] = 0
if flag:
    print("-1")