Language: C++

// スタックサイズ: 100MB

#include <iostream>
#include <fstream>
#include <vector>
#include <map>
#include <unordered_map>
#include <string>
#include <cmath>
#include <cstdio>
#include <algorithm>
#include <functional>
#include <numeric>
#include <iomanip>
#include <queue>
#include <list>
#include <set>
using namespace std;

typedef int64_t ll;
typedef vector<ll> vll;
typedef pair<ll, ll> pll;
const ll INF = 1000000000000000000;
#define fori(i, a, b) for (ll i = (a); i < (b); ++i)
#define ford(i, a, b) for (ll i = (b - 1); (a) <= i; --i)
#define rep(i, n) fori(i, 0, n)
#define all(v) (v).begin(), (v).end()
#define fst first
#define snd second
ll pw(ll x, ll y) { ll r = 1;  rep(i, y) { r *= x; }; return r; }


int main() {

	ll n, m, N, M;
	cin >> n >> m;
	N = min(n, m), M = max(n, m);


	if (4 <= N) cout << (N - 4) * (M - 4) + 2 * ((N - 4) + (M - 4)) + 4 << endl;
	else if (N == 2) cout << 0 << endl;
	else cout << max(0ll, M - 4) + 2 << endl;

}

Compiler output:
a.cc: In function 'int main()':
a.cc:42:25: error: no matching function for call to 'max(long long int, ll)'
   42 |         else cout << max(0ll, M - 4) + 2 << endl;
      |                      ~~~^~~~~~~~~~~~
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:3:
/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:42:25: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'll' {aka 'long int'})
   42 |         else cout << max(0ll, M - 4) + 2 << endl;
      |                      ~~~^~~~~~~~~~~~
/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:11:
/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:42:25: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   42 |         else cout << max(0ll, M - 4) + 2 << endl;
      |                      ~~~^~~~~~~~~~~~