Compilare: user.cpp: In function ‘int main()’: user.cpp:37:50: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int k1 = 0, k2 = 1; k2 < v.size(); k1++, k2 = k1 + 1) { ^ user.cpp:38:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (k2 < v.size() && v[k1] == v[k2]) k2++; ^ user.cpp:12:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("omogene.in","r",stdin); ^ user.cpp:13:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("omogene.out","w",stdout); ^