Compilare: user.cpp: In function ‘bool read_data()’: user.cpp:124:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] (void) scanf("%zu", &C); ^ user.cpp:131:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] (void) scanf("%zu", &N); ^ user.cpp:144:56: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] { (void) scanf("%zu %zu %zu %zu", &x0, &y0, &x1, &y1); ^ user.cpp:155:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] (void) scanf("%zu", &M); ^ user.cpp:164:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] { (void) scanf("%zu", &c); ^ user.cpp: In function ‘bool demo()’: user.cpp:257:51: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] (void) ::std::freopen ("geamuri.in", "r", stdin); ^ user.cpp:258:53: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] (void) ::std::freopen ("geamuri.out", "r", stdout); ^