Compilare: user.cpp: In function ‘int main()’: user.cpp:30:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < nr.size(); i++) ~~^~~~~~~~~~~ user.cpp:8:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("unter.in", "r", stdin); ^ user.cpp:9:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("unter.out", "w", stdout); ^