Language: C++

v#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define all(vec) vec.begin(), vec.end()
#define END return 0
typedef int64_t ll;
const int mod7 = 1e9 + 7;
const int mod9 = 1e9 + 9;
const int inf = 1 << 30;
const ll INF = 1LL << 60;
template<typename T> T gcd(T a, T b) {return b ? gcd(b, a % b) : abs(a);}
template<typename T> T lcm(T a, T b) {return a / gcd(a, b) * b;}
template<typename T> bool chmax(T &a, T b) {if (a < b) {a = b; return true;} return false;}
template<typename T> bool chmin(T &a, T b) {if (a > b) {a = b; return true;} return false;}
template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val) {fill((T*)array, (T*)(array+N), val);}

int main() {
    string n;
    cin >> n;
    ll sum = 0;
    for (char c : n)
        sum += (c - '0');
    if (sum % 9 == 0) cout << "Yes" << endl;
    else cout << "No" << 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:6:9: error: 'int64_t' does not name a type
    6 | typedef int64_t ll;
      |         ^~~~~~~
a.cc:1:1: note: 'int64_t' is defined in header '<cstdint>'; this is probably fixable by adding '#include <cstdint>'
  +++ |+#include <cstdint>
    1 | v#include <bits/stdc++.h>
a.cc:10:7: error: 'll' does not name a type; did you mean 'all'?
   10 | const ll INF = 1LL << 60;
      |       ^~
      |       all
a.cc:15:22: error: 'size_t' has not been declared
   15 | template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val) {fill((T*)array, (T*)(array+N), val);}
      |                      ^~~~~~
a.cc:15:65: error: 'N' was not declared in this scope
   15 | template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val) {fill((T*)array, (T*)(array+N), val);}
      |                                                                 ^
a.cc:15:49: error: variable or field 'Fill' declared void
   15 | template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val) {fill((T*)array, (T*)(array+N), val);}
      |                                                 ^~~~
a.cc:15:58: error: 'array' was not declared in this scope
   15 | template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val) {fill((T*)array, (T*)(array+N), val);}
      |                                                          ^~~~~
a.cc:15:65: error: 'N' was not declared in this scope
   15 | template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val) {fill((T*)array, (T*)(array+N), val);}
      |                                                                 ^
a.cc:15:69: error: expected primary-expression before 'const'
   15 | template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val) {fill((T*)array, (T*)(array+N), val);}
      |                                                                     ^~~~~
a.cc: In function 'int main()':
a.cc:18:5: error: 'string' was not declared in this scope
   18 |     string n;
      |     ^~~~~~
a.cc:19:5: error: 'cin' was not declared in this scope
   19 |     cin >> n;
      |     ^~~
a.cc:19:12: error: 'n' was not declared in this scope
   19 |     cin >> n;
      |            ^
a.cc:20:5: error: 'll' was not declared in this scope; did you mean 'all'?
   20 |     ll sum = 0;
      |     ^~
      |     all
a.cc:22:9: error: 'sum' was not declared in this scope
   22 |         sum += (c - '0');
      |         ^~~
a.cc:23:9: error: 'sum' was not declared in this scope
   23 |     if (sum % 9 == 0) cout << "Yes" << endl;
      |         ^~~
a.cc:23:23: error: 'cout' was not declared in this scope
   23 |     if (sum % 9 == 0) cout << "Yes" << endl;
      |                       ^~~~
a.cc:23:40: error: 'endl' was not declared in this scope
   23 |     if (sum % 9 == 0) cout << "Yes" << endl;
      |                                        ^~~~
a.cc:24:10: error: 'cout' was not declared in this scope
   24 |     else cout << "No" << endl;
      |          ^~~~
a.cc:24:26: error: 'endl' was not declared in this scope
   24 |     else cout << "No" << endl;
      |                          ^~~~