Compilare: user.cpp: In function ‘int main()’: user.cpp:75:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < q_left[i].size(); j++) ^ user.cpp:78:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < q_right[i].size(); j++) ^ user.cpp:50:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("qxy.in", "r", stdin); ^ user.cpp:51:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("qxy.out", "w", stdout); ^ user.cpp:53:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:55:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &v[i]); ^ user.cpp:57:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &m); ^ user.cpp:61:48: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &l, &r, &vmin, &vmax); ^