Compilare: main.cpp: In function 'int main()': main.cpp:17:27: 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 j = 0; j < f.size(); j++) | ~~^~~~~~~~~~ main.cpp:27:21: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else] 27 | else if (f[j] == ')') | ^