Language: C++

v#include <bits/stdc++.h>
typedef long long ll;
typedef long double ld;
#define rep(i,n) for(ll i=0;i<(n);i++)
#define repr(i,n) for(ll i=(n-1);i>=0;i--)
#define all(x) x.begin(),x.end()
#define br cout << "\n";
using namespace std;
const long long INF = 1e10;
const long long MOD = 1e9+7;
using Graph = vector<vector<ll>>;
using pll = pair<ll, ll>;
template<class T> inline bool chmin(T &a, T b) { if(a > b){ a = b; return true;} return false;}
template<class T> inline bool chmax(T &a, T b) { if(a < b){ a = b; return true;} return false;}
ll ceilll(ll a, ll b) {return (a + b-1) / b;} // if(a%b == 0) (a/b) + 1
ll get_digit(ll a) {ll digit = 0; while(a != 0){a /= 10; digit++;} return digit;} // a != 0
template<typename T> void vecdbg(vector<T>& v){ rep(i, v.size()){cout << v[i] << " ";} br;}
template<typename T> void vecvecdbg(vector<vector<T>>& v){ rep(i, v.size()){rep(j, v[i].size()){cout << v[i][j] << " ";} br;}}

// 0 false, 1 true 
// string number to int : -48
// a to A : -32
// ceil(a)  1.2->2.0
// c++17	g++ -std=c++17 a.cpp
// global vector -> 0 initialization
ll ans = 0;
struct PrimeNumber
{
    //O(sqrt(n))
    //sosu hantei
    bool is_prime(long long n){
        for(long long i = 2; i * i <= n; i++){
            if(n % i == 0) return false;
        }
        return n != 1;
    }

    //O(sqrt(n))  isn't sorted
    //yakusu rekkyo
    void divisor(long long n){
        //vector<long long> res;
        ll x = 0;
        for(long long i = 1; i * i <= n; i++){
            if(n % i == 0){
                //res.push_back(i);
                x++;
                if(i != n / i){
                    //res.push_back(n / i);
                    x++;
                } 
            }
        }
        if(x % 2 == 0){
            ans += x;
        }else{
            ans += x / 2 * 2 + 1;
        }
        //return res;
    }

    //O(sqrt(n))
    //soinsu bunkai
    map<long long, long long> prime_factor(long long n){
        map<long long, long long> res;
        for(long long i = 2; i * i <= n; i++){
            while(n % i == 0){
                n /= i;
                res[i]++;
            }
        }
        if(n != 1) res[n] = 1;
        return res;
    }

    //O(n log log n)
    //n madeno sosu rekkyo
    vector<long long> eratosthenes(long long n){
        vector<long long> prime;
        vector<bool> is_prime(n + 1, true);
        long long p = 0;
        is_prime[0] = false; is_prime[1] = false;
        for(long long i = 2; i <= n; i++){
            if(is_prime[i]) prime.push_back(i);
            for(long long j = 2 * i; j <= n; j += i) is_prime[j] = false;
        }
        return prime;
    }
};

int main() {
    std::cout << std::fixed << std::setprecision(15);
    ll n; cin >> n;
    PrimeNumber p;
    for(ll a = 1; a <= n-1; a++){
        ans += (n-1) / a;
    }
    /*
    for(ll c = 1; c <= n-1; c++){
        ll tmp = n-c;
        p.divisor(tmp);

        if(v.size() % 2 == 0){
            ans += v.size();
        }else{
            ans += v.size() / 2 * 2 + 1;
        }

        cout << "v " << v.size() << endl;
        ans += (v.size() + 1)/ 2;
        cout << ans << endl;

    }*/
    
    cout << ans << endl;

}

Compiler output:
a.cc:1:2: error: stray '#' in program
    1 | v#include <bits/stdc++.h>
      |  ^
a.cc:1:1: error: 'v' does not name a type
    1 | v#include <bits/stdc++.h>
      | ^
a.cc:11:15: error: 'vector' does not name a type
   11 | using Graph = vector<vector<ll>>;
      |               ^~~~~~
a.cc:12:13: error: 'pair' does not name a type
   12 | using pll = pair<ll, ll>;
      |             ^~~~
a.cc:15:1: error: 'll' does not name a type; did you mean 'ld'?
   15 | ll ceilll(ll a, ll b) {return (a + b-1) / b;} // if(a%b == 0) (a/b) + 1
      | ^~
      | ld
a.cc:16:1: error: 'll' does not name a type; did you mean 'ld'?
   16 | ll get_digit(ll a) {ll digit = 0; while(a != 0){a /= 10; digit++;} return digit;} // a != 0
      | ^~
      | ld
a.cc:17:27: error: variable or field 'vecdbg' declared void
   17 | template<typename T> void vecdbg(vector<T>& v){ rep(i, v.size()){cout << v[i] << " ";} br;}
      |                           ^~~~~~
a.cc:17:34: error: 'vector' was not declared in this scope
   17 | template<typename T> void vecdbg(vector<T>& v){ rep(i, v.size()){cout << v[i] << " ";} br;}
      |                                  ^~~~~~
a.cc:1:1: note: 'std::vector' is defined in header '<vector>'; this is probably fixable by adding '#include <vector>'
  +++ |+#include <vector>
    1 | v#include <bits/stdc++.h>
a.cc:17:42: error: expected primary-expression before '>' token
   17 | template<typename T> void vecdbg(vector<T>& v){ rep(i, v.size()){cout << v[i] << " ";} br;}
      |                                          ^
a.cc:17:45: error: 'v' was not declared in this scope
   17 | template<typename T> void vecdbg(vector<T>& v){ rep(i, v.size()){cout << v[i] << " ";} br;}
      |                                             ^
a.cc:18:27: error: variable or field 'vecvecdbg' declared void
   18 | template<typename T> void vecvecdbg(vector<vector<T>>& v){ rep(i, v.size()){rep(j, v[i].size()){cout << v[i][j] << " ";} br;}}
      |                           ^~~~~~~~~
a.cc:18:37: error: 'vector' was not declared in this scope
   18 | template<typename T> void vecvecdbg(vector<vector<T>>& v){ rep(i, v.size()){rep(j, v[i].size()){cout << v[i][j] << " ";} br;}}
      |                                     ^~~~~~
a.cc:18:37: note: 'std::vector' is defined in header '<vector>'; this is probably fixable by adding '#include <vector>'
a.cc:18:44: error: 'vector' was not declared in this scope
   18 | template<typename T> void vecvecdbg(vector<vector<T>>& v){ rep(i, v.size()){rep(j, v[i].size()){cout << v[i][j] << " ";} br;}}
      |                                            ^~~~~~
a.cc:18:44: note: 'std::vector' is defined in header '<vector>'; this is probably fixable by adding '#include <vector>'
a.cc:18:52: error: expected primary-expression before '>>' token
   18 | template<typename T> void vecvecdbg(vector<vector<T>>& v){ rep(i, v.size()){rep(j, v[i].size()){cout << v[i][j] << " ";} br;}}
      |                                                    ^~
a.cc:18:56: error: 'v' was not declared in this scope
   18 | template<typename T> void vecvecdbg(vector<vector<T>>& v){ rep(i, v.size()){rep(j, v[i].size()){cout << v[i][j] << " ";} br;}}
      |                                                        ^
a.cc:26:1: error: 'll' does not name a type; did you mean 'ld'?
   26 | ll ans = 0;
      | ^~
      | ld
a.cc:63:5: error: 'map' does not name a type
   63 |     map<long long, long long> prime_factor(long long n){
      |     ^~~
a.cc:77:5: error: 'vector' does not name a type
   77 |     vector<long long> eratosthenes(long long n){
      |     ^~~~~~
a.cc: In member function 'void PrimeNumber::divisor(long long int)':
a.cc:42:9: error: 'll' was not declared in this scope; did you mean 'ld'?
   42 |         ll x = 0;
      |         ^~
      |         ld
a.cc:46:17: error: 'x' was not declared in this scope
   46 |                 x++;
      |                 ^
a.cc:53:12: error: 'x' was not declared in this scope
   53 |         if(x % 2 == 0){
      |            ^
a.cc:54:13: error: 'ans' was not declared in this scope
   54 |             ans += x;
      |             ^~~
a.cc:56:13: error: 'ans' was not declared in this scope
   56 |             ans += x / 2 * 2 + 1;
      |             ^~~
a.cc: In function 'int main()':
a.cc:91:10: error: 'cout' is not a member of 'std'
   91 |     std::cout << std::fixed << std::setprecision(15);
      |          ^~~~
a.cc:1:1: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
  +++ |+#include <iostream>
    1 | v#include <bits/stdc++.h>
a.cc:91:23: error: 'fixed' is not a member of 'std'
   91 |     std::cout << std::fixed << std::setprecision(15);
      |                       ^~~~~
a.cc:1:1: note: 'std::fixed' is defined in header '<ios>'; this is probably fixable by adding '#include <ios>'
  +++ |+#include <ios>
    1 | v#include <bits/stdc++.h>
a.cc:91:37: error: 'setprecision' is not a member of 'std'
   91 |     std::cout << std::fixed << std::setprecision(15);
      |                                     ^~~~~~~~~~~~
a.cc:1:1: note: 'std::setprecision' is defined in header '<iomanip>'; this is probably fixable by adding '#include <iomanip>'
  +++ |+#include <iomanip>
    1 | v#include <bits/stdc++.h>
a.cc:92:5: error: 'll' was not declared in this scope; did you mean 'ld'?
   92 |     ll n; cin >> n;
      |     ^~
      |     ld
a.cc:92:11: error: 'cin' was not declared in this scope
   92 |     ll n; cin >> n;
      |           ^~~
a.cc:92:11: note: 'std::cin' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:92:18: error: 'n' was not declared in this scope
   92 |     ll n; cin >> n;
      |                  ^
a.cc:94:11: error: expected ';' before 'a'
   94 |     for(ll a = 1; a <= n-1; a++){
      |           ^~
      |           ;
a.cc:94:19: error: 'a' was not declared in this scope
   94 |     for(ll a = 1; a <= n-1; a++){
      |                   ^
a.cc:95:9: error: 'ans' was not declared in this scope
   95 |         ans += (n-1) / a;
      |         ^~~
a.cc:114:5: error: 'cout' was not declared in this scope
  114 |     cout << ans << endl;
      |     ^~~~
a.cc:114:5: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:114:13: error: 'ans' was not declared in this scope
  114 |     cout << ans << endl;
      |             ^~~
a.cc:114:20: error: 'endl' was not declared in this scope
  114 |     cout << ans << endl;
      |                    ^~~~
a.cc:1:1: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
  +++ |+#include <ostream>
    1 | v#include <bits/stdc++.h>