Compilare: main.cpp: In function 'int main()': main.cpp:20:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.size(); ++i) ~~^~~~~~~~~~ main.cpp:25:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < a.size() && a[i] != ' ') ~~^~~~~~~~~~ main.cpp:23:7: warning: variable 'poz_start' set but not used [-Wunused-but-set-variable] int poz_start = -1, cnt = 0; ^~~~~~~~~ main.cpp: In function 'bool eval()': main.cpp:75:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < b.size()) ~~^~~~~~~~~~ main.cpp:74:7: warning: 'ok' may be used uninitialized in this function [-Wmaybe-uninitialized] bool ok; ^~