Compilare: main.cpp: In function 'int main()': main.cpp:32:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 2; i < a.size(); ++i) { ~~^~~~~~~~~~ main.cpp:13:37: 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); ^ main.cpp:14:39: 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); ^