Compilare: user.cpp: In constructor ‘R::R()’: user.cpp:27:50: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] R::R(){freopen((problem+".in").c_str(),"r",stdin);B=new char[b+10];E=B+b;L();} ^ user.cpp: In member function ‘void R::L()’: user.cpp:29:45: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] void R::L(){memset(B,0,b);fread(B,1,b,stdin);p=B;} ^ user.cpp: In constructor ‘W::W()’: user.cpp:31:52: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] W::W(){freopen((problem+".out").c_str(),"w",stdout);} ^