Compilare: user.cpp: In function ‘int main()’: user.cpp:22:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<D.size();i++) { ^ user.cpp:26:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<D.size();i++) ^ user.cpp:11:17: warning: unused variable ‘x’ [-Wunused-variable] int N,M,i,k=0,x,y; ^ user.cpp:11:19: warning: unused variable ‘y’ [-Wunused-variable] int N,M,i,k=0,x,y; ^