Language: C++

#include <iostream>
#include <utility>
#include <cstdlib>
#include <cmath>
using namespace std;

int main() {
	int h, w, ans = 2147483647;
	cin >> h >> w;
	
	if(w >= 3) ans = min(ans, (w % 3 ? 1 : 0) * h); // ||
	
	if(h >= 3) ans = min(ans, (h % 3 ? 1 : 0) * w); // =
	
	long long half = floor(w / 2), a, b, c; // T
	for(int H = 1; H < h; H++){ // H is the height for the upper part
		a = H * w;
		b = (h - H) * half;
		c = (h - H) * (w - half);
		ans = min(ans, max(a, max(b, c)) - min(a, min(b, c)));
	}
	
	half = floor(w / 2); // |-
	for(int W = 1; W < w; W++){ // W is the width for the left part
		a = W * h;
		b = (w - W) * half;
		c = (w - W) * (h - half);
		ans = min(ans, max(a, max(b, c)) - min(a, min(b, c)));
	}
	
	cout << ans << endl;
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:20:26: error: no matching function for call to 'min(int&, long long int)'
   20 |                 ans = min(ans, max(a, max(b, c)) - min(a, min(b, c)));
      |                       ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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: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:20:26: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'long long int')
   20 |                 ans = min(ans, max(a, max(b, c)) - min(a, min(b, c)));
      |                       ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/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
a.cc:28:26: error: no matching function for call to 'min(int&, long long int)'
   28 |                 ans = min(ans, max(a, max(b, c)) - min(a, min(b, c)));
      |                       ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/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:28:26: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'long long int')
   28 |                 ans = min(ans, max(a, max(b, c)) - min(a, min(b, c)));
      |                       ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/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