Compilare: user.cpp: In function ‘void back(int)’: user.cpp:25:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (x==sol.size()+1) { ^ user.cpp:27:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<sol.size();i++) printf("%d ",t[i+1]); ^ user.cpp: In function ‘int main()’: user.cpp:47:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("divizori.in","r",stdin); ^ user.cpp:48:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("divizori.out","w",stdout); ^ user.cpp:50:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^