n = gets.chomp.to_i                                                                                                                    
                                                                                                                                       
ans = 0                                                                                                                                
                                                                                                                                       
                                                                                                                                       
(1...n).each do |i|                                                                                                                    
  # i == 1 の時はn-1                                                                                                                   
  # i == 2 の時は(n-1)/2                                                                                                               
  ans += (n-1)/i                                                                                                                       
end                                                                                                                                    
print ans