Language: C++

#include <bits/stdc++.h>

#define all(x) begin(x), end(x)
typedef long long ll;
using namespace std;

const ll MAXN = 1e5 + 5;
ll N;
signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cin >> N;
    vector<array<ll, 4>> probs(N);
    for (ll i = 0; i < N; i++) {
        cin >> probs[i][0] >> probs[i][1];
    }
    sort(all(probs), [](auto a, auto b) { return a[1] < b[1]; });
    set<ll> lftVals, rghtVals;
    for (ll i = 0; i < N; i++) {
        lftVals.insert(probs[i][0]);
        rghtVals.insert(probs[i][1]);
        probs[i][2] = max(0, *rghtVals.begin() - *lftVals.rbegin() + 1);
    }
    reverse(all(probs));
    lftVals.clear(), rghtVals.clear();
    for (ll i = 0; i < N; i++) {
        lftVals.insert(probs[i][0]);
        rghtVals.insert(probs[i][1]);
        probs[i][3] = max(0, *rghtVals.begin() - *lftVals.rbegin() + 1);
    }
    reverse(all(probs));
    ll ans = 0;
    for (ll i = 0; i < N; i++) {
        ans = max(probs[i][2] + probs[i + 1][3], ans);
    }
    cout << ans << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:22:26: error: no matching function for call to 'max(int, long long int)'
   22 |         probs[i][2] = max(0, *rghtVals.begin() - *lftVals.rbegin() + 1);
      |                       ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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: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:22:26: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'long long int')
   22 |         probs[i][2] = max(0, *rghtVals.begin() - *lftVals.rbegin() + 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:
/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:22:26: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
   22 |         probs[i][2] = max(0, *rghtVals.begin() - *lftVals.rbegin() + 1);
      |                       ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
a.cc:29:26: error: no matching function for call to 'max(int, long long int)'
   29 |         probs[i][3] = max(0, *rghtVals.begin() - *lftVals.rbegin() + 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:29:26: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'long long int')
   29 |         probs[i][3] = max(0, *rghtVals.begin() - *lftVals.rbegin() + 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:29:26: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
   29 |         probs[i][3] = max(0, *rghtVals.begin() - *lftVals.rbegin() + 1);
      |                       ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~