Compilare: user.cpp: In function ‘int fibo_palindrome_to_int(std::string)’: user.cpp:14:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.length(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:39:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("fibo.in", "r", stdin); ^ user.cpp:40:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("fibo.out", "w", stdout); ^