Compilare: user.cpp: In function ‘void df(int)’: user.cpp:17:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<l[k].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:26:11: warning: unused variable ‘j’ [-Wunused-variable] int i,j,m,x,y; ^ user.cpp:27:28: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d %d",&n,&m); ^ user.cpp:30:32: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d %d",&x,&y); ^