Compilare: user.cpp: In function ‘int main()’: user.cpp:18:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < a.size()) { ~~^~~~~~~~~~ user.cpp:20:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(j > a.size()) ~~^~~~~~~~~~ user.cpp:10:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("smooth2.in", "r", stdin); ^ user.cpp:11:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("smooth2.out", "w", stdout); ^