Language: C++

#include <iostream>
#include <vector>
#include <cmath>
#include <iomanip>
#include <algorithm>
#include <queue>
using namespace std;
#define rep(i,n) for(int i=0; i<(n); i++)
const int mod=1000000007;

int main() {
    long long n;
    cin>>n;
    vector<pair<long long,long long>>a(n);
    rep(i,n)cin>>a[i].first>>a[i].second;
    sort(a.begin(),a.end());
    //input
    long long ans=0;
    rep(i,n)ans=max(ans,a[i].second-a[i].first+1);
    //longest one
    long long m=n-1,cnt=0;
    for(int i=n-2;i>0;i--){
        if(a[i].second>a[m].second){
            a[i].first=mod;
            cnt++;
        }
        else m=i;
    }
    sort(a.begin(),a.end());
    rep(i,cnt)a.pop_back();
    //seiri
    long long l=a.size();
    long long lr=a[0].second,rl=a[l-1].first,lans,rans;
    rep(i,l-1){
        lans=max(0,lr-a[i].first+1);
        rans=max(0,a[i+1].second-rl+1);
        ans=max(ans,lans+rans);
    }
    cout<<ans;
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:35:17: error: no matching function for call to 'max(int, long long int)'
   35 |         lans=max(0,lr-a[i].first+1);
      |              ~~~^~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/string:51,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:35:17: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'long long int')
   35 |         lans=max(0,lr-a[i].first+1);
      |              ~~~^~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61,
                 from a.cc:5:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:35:17: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
   35 |         lans=max(0,lr-a[i].first+1);
      |              ~~~^~~~~~~~~~~~~~~~~~~
a.cc:36:17: error: no matching function for call to 'max(int, long long int)'
   36 |         rans=max(0,a[i+1].second-rl+1);
      |              ~~~^~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:36:17: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'long long int')
   36 |         rans=max(0,a[i+1].second-rl+1);
      |              ~~~^~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:36:17: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
   36 |         rans=max(0,a[i+1].second-rl+1);
      |              ~~~^~~~~~~~~~~~~~~~~~~~~~