Compilare: user.cpp: In function ‘int main()’: user.cpp:18:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a.size();++i) ^ user.cpp:9:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("permut.in","r",stdin); ^ user.cpp:10:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("permut.out","w",stdout); ^ user.cpp:13:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:14:57: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(int i=0; i<n; ++i) scanf("%d",&t),a.push_back(t); ^ user.cpp:15:57: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(int i=0; i<n; ++i) scanf("%d",&t),b.push_back(t); ^