Compilare: user.cpp: In function ‘void back()’: user.cpp:24: warning: format ‘%ld’ expects type ‘long int’, but argument 2 has type ‘int’ user.cpp:24: warning: format ‘%ld’ expects type ‘long int’, but argument 3 has type ‘int’ user.cpp:24: warning: format ‘%ld’ expects type ‘long int’, but argument 4 has type ‘int’ user.cpp: In function ‘int main()’: user.cpp:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:30: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:37: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result