Compilare: user.cpp: In function ‘int main()’: user.cpp:9: warning: statement has no effect user.cpp:26: warning: format ‘%d’ expects type ‘int’, but argument 2 has type ‘long long int’ user.cpp:8: warning: unused variable ‘n’ user.cpp:8: warning: unused variable ‘i’ user.cpp:8: warning: unused variable ‘k’ 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: ‘c’ may be used uninitialized in this function