Compilare: user.cpp: In function ‘int main(int, const char**)’: user.cpp:17:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (j < b.size() && ans.size() <= 100) { ^ user.cpp:19:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int k = 0; k < a.size(); ++k) { ^ 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("strmatch.in", "r", stdin); ^ user.cpp:9:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("strmatch.out", "w", stdout); ^