Compilare: user.cpp: In function ‘void read()’: user.cpp:33:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("huffman.in", "r", stdin); ^ user.cpp: In function ‘void cit(long long int&)’: user.cpp:25:45: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(ax, 1, dim, stdin), pz = 0; ^ user.cpp:29:45: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(ax, 1, dim, stdin), pz = 0; ^ user.cpp: In function ‘void solve()’: user.cpp:74:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("huffman.out", "w", stdout); ^