Compilare: user.cpp: In function ‘void Read()’: user.cpp:15: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void Build()’: user.cpp:70: warning: comparison between signed and unsigned integer expressions user.cpp:72: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void Print()’: user.cpp:132: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result