Compilare: main.cpp: In function 'int main()': main.cpp:19:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 19 | for (int i = 0; i <= s.size(); i++) | ~~^~~~~~~~~~~ main.cpp:36:20: warning: operation on 'top' may be undefined [-Wsequence-point] 36 | st[++top] = min(st[top], x); | ^~~~~ main.cpp:42:20: warning: operation on 'top' may be undefined [-Wsequence-point] 42 | st[++top] = max(st[top], x); | ^~~~~