Compilare: user.cpp: In function ‘int main()’: user.cpp:545: warning: comparison between signed and unsigned integer expressions user.cpp:391: warning: unused variable ‘tstart’ user.cpp:393: warning: unused variable ‘lastj’ user.cpp:396: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:398: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:400: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:548: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result