Compilare: user.cpp: In function ‘int main()’: user.cpp:57: warning: format ‘%lu’ expects type ‘long unsigned int’, but argument 3 has type ‘ptrdiff_t’ user.cpp:57: warning: format ‘%lu’ expects type ‘long unsigned int’, but argument 4 has type ‘ptrdiff_t’ user.cpp:13: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:14: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result