Compilare: user.cpp: In function ‘void df(int)’: user.cpp:50:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<C[x].size();i++) ^ user.cpp: In function ‘void readdata()’: user.cpp:18:30: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf (f,"%d%d%d",&n,&m,&k); ^ user.cpp:21:26: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf (f,"%d%d",&a,&b); ^ user.cpp:32:36: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf (f,"%d%d%d%d",&a,&b,&c,&d); ^