centru.cpp: In function 'void read()': centru.cpp:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result centru.cpp:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result centru.cpp:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result centru.cpp: In function 'void solve()': centru.cpp:74: warning: unused variable 'i' centru.cpp:74: warning: unused variable 'j' centru.cpp: In function 'void write()': centru.cpp:91: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result