k = gets.chomp.to_i

if k % 7 == 0 
  puts 1
  exit
end
count = 0
i = 0
while true do
  i = i * 10 + 1
  i %= k
  count += 1
  if i == 0
    break
  elsif count > 10 ** 6
    puts -1
    exit
  end
end

puts count
