Compilare: user.cpp: In function ‘void backtr(int)’: user.cpp:25:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (pos == freq[0].size()) { ^ user.cpp: In function ‘int main()’: user.cpp:45:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("culori4.in", "r", stdin); ^ user.cpp:46:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("culori4.out", "w", stdout); ^