Compilare: user.cpp: In function ‘void find(int&, std::vector<std::vector<long long int> >&, std::vector<std::vector<long long int> >&, int, int, int)’: user.cpp:66:15: warning: unused variable ‘a’ [-Wunused-variable] int a = i - 1; ^ user.cpp:67:15: warning: unused variable ‘b’ [-Wunused-variable] int b = j - 1; ^ user.cpp: In member function ‘char InParser::read_ch()’: user.cpp:17:40: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buff, 1, 4096, fin); ^