Compilare: user.cpp: In function ‘void add(int)’: user.cpp:26:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < M[nr].size(); ++i) /// verific daca mai exista elementul in multime ^ user.cpp: In function ‘void remove1(int)’: user.cpp:33:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < M[nr].size(); ++i) /// caut elementul ^ user.cpp: In function ‘bool query(int)’: user.cpp:43:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < M[nr].size(); ++i) ^