Compilare: main.cpp: In function 'void solve(int)': main.cpp:18:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(index == rd.size()) return; ~~~~~~^~~~~~~~~~~~ main.cpp:41:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(index < rd.size() && (rd[index] == '*' || rd[index] == '/')) ~~~~~~^~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:58:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(index < rd.size()) ~~~~~~^~~~~~~~~~~