Compilare: user.cpp: In function ‘int main()’: user.cpp:29:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); ++i) { ^ user.cpp:51:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v1.size(); ++i) cout << v1[i] << ' '; ^ user.cpp:53:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v2.size(); ++i) cout << v2[i] << ' '; ^ user.cpp:7:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("brackets.in", "rt", stdin); ^ user.cpp:8:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("brackets.out", "wt", stdout); ^