Compilare: user.cpp: In function ‘int select_next_interval(const std::vector<std::pair<int, int> >&, int, int)’: user.cpp:25:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (intervals.size() == next) ~~~~~~~~~~~~~~~~~^~~~~~~ user.cpp: In function ‘void read(int&, std::vector<std::pair<int, int> >&)’: user.cpp:15:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d", &n); ^ user.cpp:17:34: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d%d", &x, &y); ^