Compilare: main.cpp: In function 'int main()': main.cpp:17:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 17 | for (int i = 0 ; i < s.size() ; i++) | ~~^~~~~~~~~~ main.cpp:28:20: warning: operation on 'top' may be undefined [-Wsequence-point] 28 | st[++top] = min(st[top-1],x); | ^~~~~ main.cpp:30:20: warning: operation on 'top' may be undefined [-Wsequence-point] 30 | st[++top] = max(st[top-1],x); | ^~~~~