Compilare: user.cpp: In function ‘void readdata()’: user.cpp:17: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, 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:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void bfs()’: user.cpp:29: warning: unused variable ‘j’ user.cpp: In function ‘int main()’: user.cpp:45: warning: unused variable ‘n’ user.cpp:45: warning: unused variable ‘i’ user.cpp:45: warning: unused variable ‘m’ user.cpp:45: warning: unused variable ‘x’ user.cpp:45: warning: unused variable ‘xx’ user.cpp:45: warning: unused variable ‘niv’ user.cpp:45: warning: unused variable ‘j’ user.cpp:44: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result