Language: C++

/* Aditya0412 */
#include <bits/stdc++.h>
using namespace std; 
typedef long long int ll;
#define pb push_back 
#define ve vector
#define vii vector < int >
#define vll vector < ll > 
#define pii pair < int , int >
#define pll pair < ll , ll >
#define vpl vector < pll >
#define fi first
#define all(a)      (a).begin(),(a).end()
#define si(x)       (int)((x).size())
#define debug(x)    cout<<#x<<" is "<<(x)<<endl;cout.flush();  
#define se second 
#define endl        '\n'
#define f(i,a,b)    for(int i=a;i<b;i++)
#define mem(a,x)          memset(a,x,sizeof(a))

// === Debug macro starts here ===

int recur_depth = 0;
#ifdef DEBUG
#define dbg(x) {++recur_depth; auto x_=x; --recur_depth; cerr<<string(recur_depth, '\t')<<"\e[91m"<<__func__<<":"<<__LINE__<<"\t"<<#x<<" = "<<x_<<"\e[39m"<<endl;}
#else
#define dbg(x)
#endif
template<typename Ostream, typename Cont>
typename enable_if<is_same<Ostream,ostream>::value, Ostream&>::type operator<<(Ostream& os,  const Cont& v){
    os<<"["; 
    for(auto& x:v){os<<x<<", ";}
    return os<<"]";
}
template<typename Ostream, typename ...Ts>
Ostream& operator<<(Ostream& os,  const pair<Ts...>& p){
    return os<<"{"<<p.first<<", "<<p.second<<"}";
}

// === Debug macro ends here ===


// const ll mod=998244353;
const ll mod = 1000000000+7;
const ll N=1000000+6;
#define M_PI           3.14159265358979323846
void inp(ll *arr,ll n)
{
  for(int i=0;i<n;i++)
    cin>>arr[i];
}
void inp_mat(ll *arr,ll n,ll m)
{
    for(int i=0;i<n;i++)
      for(int j=0;j<m;j++)
        {
          ll x;cin>>x;
          *((arr+i*m) + j)=x;
        }
}
// syntax for inp_mat inp_mat((ll *)arr,n,m);
// int x2[]={+1,-1,+0,+0};
// int y2[]={+0,+0,+1,-1};

int main() 
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    //  #ifndef ONLINE_JUDGEc
    //   freopen ("INPUT.txt" , "r" , stdin);
    //   freopen ("OUTPUT.txt", "w" , stdout);
    // #endif     
    int t=1;
    // cin>>t;
    while(t--)
    {
        string s;cin>>s;
        ll s=0;
        f(i,0,si(s))
        {
          s+=(s[i]-'0');
        }
        if(s%9)
        cout<<"NO";
        else
        {
          cout<<"YES";
        }
        
    }
} 

Compiler output:
a.cc: In function 'int main()':
a.cc:79:12: error: conflicting declaration 'll s'
   79 |         ll s=0;
      |            ^
a.cc:78:16: note: previous declaration as 'std::string s'
   78 |         string s;cin>>s;
      |                ^
a.cc:84:13: error: no match for 'operator%' (operand types are 'std::string' {aka 'std::__cxx11::basic_string<char>'} and 'int')
   84 |         if(s%9)
      |            ~^~
      |            | |
      |            | int
      |            std::string {aka std::__cxx11::basic_string<char>}
In file included from /usr/include/c++/14/valarray:605,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:166,
                 from a.cc:2:
/usr/include/c++/14/bits/valarray_after.h:409:5: note: candidate: 'template<class _Dom1, class _Dom2> std::_Expr<std::__detail::_BinClos<std::__modulus, std::_Expr, std::_Expr, _Dom1, _Dom2>, typename std::__fun<std::__modulus, typename _Dom1::value_type>::result_type> std::operator%(const _Expr<_Dom1, typename _Dom1::value_type>&, const _Expr<_Dom2, typename _Dom2::value_type>&)'
  409 |     _DEFINE_EXPR_BINARY_OPERATOR(%, struct std::__modulus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:409:5: note:   template argument deduction/substitution failed:
a.cc:84:14: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   84 |         if(s%9)
      |              ^
/usr/include/c++/14/bits/valarray_after.h:409:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__modulus, std::_Expr, std::_Constant, _Dom, typename _Dom::value_type>, typename std::__fun<std::__modulus, typename _Dom1::value_type>::result_type> std::operator%(const _Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)'
  409 |     _DEFINE_EXPR_BINARY_OPERATOR(%, struct std::__modulus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:409:5: note:   template argument deduction/substitution failed:
a.cc:84:14: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   84 |         if(s%9)
      |              ^
/usr/include/c++/14/bits/valarray_after.h:409:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__modulus, std::_Constant, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__modulus, typename _Dom1::value_type>::result_type> std::operator%(const typename _Dom::value_type&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  409 |     _DEFINE_EXPR_BINARY_OPERATOR(%, struct std::__modulus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:409:5: note:   template argument deduction/substitution failed:
a.cc:84:14: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'int'
   84 |         if(s%9)
      |              ^
/usr/include/c++/14/bits/valarray_after.h:409:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__modulus, std::_Expr, std::_ValArray, _Dom, typename _Dom::value_type>, typename std::__fun<std::__modulus, typename _Dom1::value_type>::result_type> std::operator%(const _Expr<_Dom1, typename _Dom1::value_type>&, const valarray<typename _Dom::value_type>&)'
  409 |     _DEFINE_EXPR_BINARY_OPERATOR(%, struct std::__modulus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:409:5: note:   template argument deduction/substitution failed:
a.cc:84:14: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   84 |         if(s%9)
      |              ^
/usr/include/c++/14/bits/valarray_after.h:409:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__modulus, std::_ValArray, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__modulus, typename _Dom1::value_type>::result_type> std::operator%(const valarray<typename _Dom::value_type>&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  409 |     _DEFINE_EXPR_BINARY_OPERATOR(%, struct std::__modulus)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:409:5: note:   template argument deduction/substitution failed:
a.cc:84:14: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'int'
   84 |         if(s%9)
      |              ^
/usr/include/c++/14/valarray:1200:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__modulus, std::_ValArray, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__modulus, _Tp>::result_type> std::operator%(const valarray<_Tp>&, const valarray<_Tp>&)'
 1200 | _DEFINE_BINARY_OPERATOR(%, __modulus)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1200:1: note:   template argument deduction/substitution failed:
a.cc:84:14: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::valarray<_Tp>'
   84 |         if(s%9)
      |              ^
/usr/include/c++/14/valarray:1200:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__modulus, std::_ValArray, std::_Constant, _Tp, _Tp>, typename std::__fun<std::__modulus, _Tp>::result_type> std::operator%(const valarray<_Tp>&, const typename valarray<_Tp>::value_type&)'
 1200 | _DEFINE_BINARY_OPERATOR(%, __modulus)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1200:1: note:   template argument deduction/substitution failed:
a.cc:84:14: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::valarray<_Tp>'
   84 |         if(s%9)
      |              ^
/usr/include/c++/14/valarray:1200:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__modulus, std::_Constant, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__modulus, _Tp>::result_type> std::operator%(const typename valarray<_Tp>::value_type&, const valarray<_Tp>&)'
 1200 | _DEFINE_BINARY_OPERATOR(%, __modulus)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1200:1: note:   template argument deduction/substitution failed:
a.cc:84:14: note:   mismatched types 'const std::valarray<_Tp>' and 'int'
   84 |         if(s%9)
      |              ^