Compilare: main.cpp: In function 'void solve()': main.cpp:223:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<b.length();i++){ ~^~~~~~~~~~~ main.cpp: In function 'type get_type(const string&)': main.cpp:54:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ main.cpp: In function 'operation get_operation(const string&)': main.cpp:106:1: warning: control reaches end of non-void function [-Wreturn-type] } ^