Compilare: main.cpp: In function 'std::__cxx11::string solutie()': main.cpp:18:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (poz < sir.size() && sir[poz] != ')' && sir[poz] != ']' && sir[poz] != '*') ~~~~^~~~~~~~~~~~ main.cpp:26:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (poz < sir.size() && '0' <= sir[poz] && sir[poz] <= '9') ~~~~^~~~~~~~~~~~ main.cpp:80:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (poz < sir.size() && 'a' <= sir[poz] && sir[poz] <= 'z') ~~~~^~~~~~~~~~~~