Compilare: user.cpp: In function ‘int main()’: user.cpp:99:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (k = 0; k < curr_query_intervals.size(); k++) { ^ user.cpp:124:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (k = 0; k < curr_query_intervals.size(); k++) { ^ user.cpp:133:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < solutions.size(); i++) { ^ user.cpp:61:30: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pq.in", "r", stdin); ^ user.cpp:62:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pq.out", "w", stdout); ^ user.cpp:64:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &query_intervals_len); ^ user.cpp:66:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &input[i].val); ^ user.cpp:83:53: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n", &query_intervals[i].left, &right); ^