Compilare: user.cpp: In function ‘void read(ll&)’: user.cpp:13:57: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] if(++p == dim) fread(buff, 1, dim, stdin), p = 0; ^ user.cpp:16:57: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] if(++p == dim) fread(buff, 1, dim, stdin), p = 0; ^ user.cpp: In function ‘int main()’: user.cpp:41:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dif2.in","r",stdin); ^ user.cpp:42:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dif2.out","w",stdout); ^