Compilare: user.cpp: In function ‘int main()’: user.cpp:9: warning: format ‘%ld’ expects type ‘long int’, but argument 2 has type ‘int’ user.cpp:5: warning: unused variable ‘i’ user.cpp:5: warning: unused variable ‘s’ user.cpp:5: warning: unused variable ‘u’ user.cpp:6: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:7: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:8: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result