Compilare: main.cpp: In function 'int main()': main.cpp:115:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v.size (); i += 2) { ~~^~~~~~~~~~~ main.cpp:133:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < ans.size () - 1; i++) { ~~^~~~~~~~~~~~~~~~~ main.cpp:83:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("ratway.in", "r", stdin); ^ main.cpp:85:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("ratway.out", "w", stdout); ^