Compilare: user.cpp: In function ‘void loop(std::vector<int>, int)’: user.cpp:20:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < elements.size(); ++i) ~~^~~~~~~~~~~~~~~~~ user.cpp:24:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < elements.size(); ++j) ~~^~~~~~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:33:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("permutari.in", "r", stdin); ^ user.cpp:34:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("permutari.out", "w", stdout); ^ user.cpp:35:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^