Language: C++

#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#define REP(i,n) for(int i=0;i<n;i++)
#define REPP(i,n) for(int i=1;i<=n;i++)
#define ALL(obj) (obj).begin(), (obj).end()
const double PI = acos(-1);
const double EPS = 1e-15;
long long INF=(long long)1E17;
#define i_7 (long long)(1E9+7)
long mod(long a){
    long long c=a%i_7;
    if(c>=0)return c;
    return c+i_7;
}
using namespace std;
bool prime_(int n){
  if(n==1){
    return false;
  }else if(n==2){
    return true;
  }else{
    for(int i=2;i<=sqrt(n);i++){
      if(n%i==0){
        return false;
      }
    }
    return true;
  }
}

long long gcd_(long long a, long long b){
  if(a<b){
    swap(a,b);
  }
  if(a%b==0){
    return b;
  }else{
    return gcd_(b,a%b);
  }
}
 
long long lcm_(long long x, long long y){
  return (x/gcd_(x,y))*y;
}

int main(){
  
  int n;
  string s;
  cin>>n;
  cin>>s;
  //map<string,int> mp;//sの部分文字列とその個数
  //map<string,int> bound_;//現れる一番左の文字列の右端
  string temp;
  bool flag = false;
  int ans = 0;
  for(int l = n;l>=1;l--){//取る部分文字列の長さ
    set<string> ss;
    REP(i,n){//部分文字列の最初の1文字のインデックス
      if(i+l-1>n-1)break;
      temp = s.substr(i,l);
      //mp[temp]++;
      auto it = ss.find(temp);
      if(it ==s.end()){
        s.insert(temp);
        bound_[temp] = i+l-1;
      }else{
        if(bound_[temp]<i){
          ans = l;
          flag = true;
          break;
        }
      }
    }
    if(flag)break;
  }
  cout<<ans<<endl;
    
  return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:64:13: error: no match for 'operator==' (operand types are 'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' and 'std::__cxx11::basic_string<char>::iterator')
   64 |       if(it ==s.end()){
      |          ~~ ^~~~~~~~~
      |          |         |
      |          |         std::__cxx11::basic_string<char>::iterator
      |          std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >
In file included from /usr/include/c++/14/regex:68,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:181,
                 from a.cc:1:
/usr/include/c++/14/bits/regex.h:1103:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1103 |     operator==(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1103:5: note:   template argument deduction/substitution failed:
a.cc:64:21: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   64 |       if(it ==s.end()){
      |                     ^
/usr/include/c++/14/bits/regex.h:1199:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator==(__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const sub_match<_BiIter>&)'
 1199 |     operator==(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1199:5: note:   template argument deduction/substitution failed:
a.cc:64:21: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'
   64 |       if(it ==s.end()){
      |                     ^
/usr/include/c++/14/bits/regex.h:1274:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator==(const sub_match<_BiIter>&, __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)'
 1274 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1274:5: note:   template argument deduction/substitution failed:
a.cc:64:21: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   64 |       if(it ==s.end()){
      |                     ^
/usr/include/c++/14/bits/regex.h:1366:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1366 |     operator==(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1366:5: note:   template argument deduction/substitution failed:
a.cc:64:21: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   64 |       if(it ==s.end()){
      |                     ^
/usr/include/c++/14/bits/regex.h:1441:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1441 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1441:5: note:   template argument deduction/substitution failed:
a.cc:64:21: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   64 |       if(it ==s.end()){
      |                     ^
/usr/include/c++/14/bits/regex.h:1534:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1534 |     operator==(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1534:5: note:   template argument deduction/substitution failed:
a.cc:64:21: note:   'std::__cxx11::basic_string<char>::iterator' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   64 |       if(it ==s.end()){
      |                     ^
/usr/include/c++/14/bits/regex.h:1613:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1613 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1613:5: note:   template argument deduction/substitution failed:
a.cc:64:21: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   64 |       if(it ==s.end()){
      |                     ^
/usr/include/c++/14/bits/regex.h:2186:5: note: candidate: 'template<class _Bi_iter, class _Alloc> bool std::__cxx11::operator==(const match_results<_BiIter, _Alloc>&, const match_results<_BiIter, _Alloc>&)'
 2186 |     operator==(const match_results<_Bi_iter, _Alloc>& __m1,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:2186:5: note:   template argument deduction/substitution failed:
a.cc:64:21: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::__cxx11::match_results<_BiIter, _Alloc>'
   64 |       if(it ==s.end()){
      |                     ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/bits/stl_pair.h:1033:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator==(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1033 |     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1033:5: note:   template argument deduction/substitution failed:
a.cc:64:21: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::pair<_T1, _T2>'
   64 |       if(it ==s.end()){
      |                     ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:441:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  441 |     operator==(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:441:5: note:   template argument deduction/substitution failed:
a.cc:64:21: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::reverse_iterator<_Iterator>'
   64 |       if(it ==s.end()){
      |                     ^
/usr/include/c++/14/bits/stl_iterator.h:486:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  486 |     operator==(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:486:5: note:   template argument deduction/substitution failed:
a.cc:64:21: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::reverse_iterator<_Iterator>'
   64 |       if(it ==s.end()){
      |                     ^
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1667 |     operator==(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note:   template argument deduction/substitution failed:
a.cc:64:21: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::move_iterator<_IteratorL>'
   64 |       if(it ==s.end()){
      |                     ^
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1737 |     operator==(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note:   template argument deduction/substitution failed:
a.cc:64:21: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::move_iterator<_IteratorL>'
   64 |       if(it ==s.end()){
      |                     ^
In file included from /usr/include/c++/14/bits/char_traits.h:42,
                 from /usr/include/c++/14/string:42,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/bits/postypes.h:192:5: note: candidate: 'template<class _StateT> bool std::operator==(const fpos<_StateT>&, const fpos<_StateT>&)'
  192 |     operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/postypes.h:192:5: note:   template argument deduction/substitution failed:
a.cc:64:21: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::fpos<_StateT>'
   64 |       if(it ==s.end()){
      |                     ^
In file included from /usr/include/c++/14/string:43:
/usr/include/c++/14/bits/allocator.h:235:5: note: candidate: 'template<class _T1, class _T2> bool std::operator==(const allocator<_CharT>&, const allocator<_T2>&)'
  235 |     operator==(const allocator<_T1>&, const allocator<_T2>&)
      |     ^~~~~~~~
/usr/include/c++/14/bits/allocator.h:235:5: note:   template argument deduction/substitution failed:
a.cc:64:21: note:   'std::_Rb_tree_const_iterator<std::__cxx11::basic_string<char> >' is not derived from 'const std::allocator<_CharT>'
   64 |       if(it ==s.end()){
      |                     ^
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54:
/usr/include/c++/14/string_view:629:5: not