Compilare: user.cpp: In function ‘void back(int)’: user.cpp:17:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = sol[k-1] + 1; i < V.size(); i++) { ^ user.cpp: In function ‘int main()’: user.cpp:57:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < V.size(); i++) { ^ user.cpp:26:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("produs4.in", "r", stdin); ^ user.cpp:27:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("produs4.out", "w", stdout); ^ user.cpp:28:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d\n", &t); ^ user.cpp:35:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &n); ^ user.cpp:37:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &T[i]); ^