Compilare: main.cpp: In function 'bool cmp(const std::vector<int>&, const std::vector<int>&)': main.cpp:13:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < a.size() && a[i] < b[i]) ~~^~~~~~~~~~ main.cpp:15:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] return i == a.size(); ~~^~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:19:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("album.in", "r", stdin); ^ main.cpp:20:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("album.out", "w", stdout); ^