Compilare: user.cpp: In function ‘void read()’: user.cpp:21: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, 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: In function ‘void write()’: user.cpp:74: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp: In function ‘int main()’: user.cpp:89: warning: format ‘%d’ expects type ‘int’, but argument 2 has type ‘long long int’ user.cpp:86: warning: unused variable ‘i’