Compilare: user.cpp: In function ‘int add(int)’: user.cpp:13:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<has[r].size();++i) ^ user.cpp: In function ‘int show(int)’: user.cpp:29:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<has[r].size();++i) ^ user.cpp: In function ‘int add(int)’: user.cpp:17:1: warning: control reaches end of non-void function [-Wreturn-type] } ^