Language: C++

#include "bits/stdc++.h"
using namespace std;

//

#define RESIDUE(u,v) (capacity[u][v] - flow[u][v])
#define RCOST(u,v) (cost[u][v] + h[u] - h[v])
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)   FOR(i,0,n)
#define LL long long

string s;
int k;

vector<string> v;

int main(){
  cin>>s>>k;

  char headchar='A',dum;
  
  while(true){
    // determine head char
    dum=headchar;
    headchar = 'z'+1;
    REP(i,s.size()){
      if(s[i]>dum && headchar>s[i]){
	headchar=s[i];
      }
    }

    REP(i,s.size()){
      if(s[i]!=headchar) continue;
      FOR(j,1,min(s.size()-i+1,6)){
	v.push_back(s.substr(i,j));
      }
    }

    sort(v.begin(),v.end());
    v.erase(unique(v.begin(), v.end()), v.end());
    if(v.size()>=k) break;
  }
  cout<<v[k-1]<<endl;
  return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:34:18: error: no matching function for call to 'min(std::__cxx11::basic_string<char>::size_type, int)'
   34 |       FOR(j,1,min(s.size()-i+1,6)){
      |               ~~~^~~~~~~~~~~~~~~~
a.cc:8:37: note: in definition of macro 'FOR'
    8 | #define FOR(i,a,b) for(int i=(a);i<(b);++i)
      |                                     ^
In file included from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:233:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::min(const _Tp&, const _Tp&)'
  233 |     min(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:233:5: note:   template argument deduction/substitution failed:
a.cc:34:18: note:   deduced conflicting types for parameter 'const _Tp' ('long unsigned int' and 'int')
   34 |       FOR(j,1,min(s.size()-i+1,6)){
      |               ~~~^~~~~~~~~~~~~~~~
a.cc:8:37: note: in definition of macro 'FOR'
    8 | #define FOR(i,a,b) for(int i=(a);i<(b);++i)
      |                                     ^
/usr/include/c++/14/bits/stl_algobase.h:281:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::min(const _Tp&, const _Tp&, _Compare)'
  281 |     min(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:281:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:5686:5: note: candidate: 'template<class _Tp> constexpr _Tp std::min(initializer_list<_Tp>)'
 5686 |     min(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5686:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5696:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::min(initializer_list<_Tp>, _Compare)'
 5696 |     min(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5696:5: note:   template argument deduction/substitution failed:
a.cc:34:18: note:   mismatched types 'std::initializer_list<_Tp>' and 'long unsigned int'
   34 |       FOR(j,1,min(s.size()-i+1,6)){
      |               ~~~^~~~~~~~~~~~~~~~
a.cc:8:37: note: in definition of macro 'FOR'
    8 | #define FOR(i,a,b) for(int i=(a);i<(b);++i)
      |                                     ^