Compilare: user.cpp: In function ‘void prepare_for(int)’: user.cpp:30:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < intervs.size(); ++ i) { ^ user.cpp: In function ‘int get_who(int)’: user.cpp:53:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < intervs.size(); ++ i) { ^ user.cpp: In function ‘void rev(int, int)’: user.cpp:78:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < intervs.size(); ++ i) { ^ user.cpp: In function ‘void unload()’: user.cpp:109:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < intervs.size(); ++ i) ^