Compilare: user.cpp: In function ‘void read(long long int&)’: user.cpp:13:51: 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:16:51: 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:50:32: 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:51:34: 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); ^