Compilare: user.cpp: In function ‘int main()’: user.cpp:22: 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 ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:44: warning: dereferencing pointer ‘__y’ does break strict-aliasing rules /usr/include/c++/4.4/bits/stl_tree.h:493: note: initialized from here