Compilare: user.cpp: In function ‘int main()’: user.cpp:581: warning: comparison between signed and unsigned integer expressions user.cpp:420: warning: unused variable ‘tstart’ user.cpp:422: warning: unused variable ‘lastj’ user.cpp:425: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:427: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:429: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:584: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result