Compilare: user.cpp: In function ‘void write_data()’: user.cpp:82:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<sol.size();i++) write(sol[i]),putChar(' '); ^ user.cpp: In function ‘void read(int&)’: user.cpp:17:96: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] while(!isdigit(buff[pos])) if(++pos == buff_size) fread(buff, 1,buff_size, stdin), pos = 0; ^ user.cpp:22:73: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] if(++pos == buff_size) fread(buff, 1, buff_size, stdin), pos = 0; ^