Compilare: user.cpp: In function ‘bool okp(int)’: user.cpp:19:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < u[y].size(); i++) ^ user.cpp: In function ‘void marcare(int, int)’: user.cpp:35:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < u[y].size(); i ++) ^ user.cpp:41:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < u[y].size(); i ++) ^