Compilare: user.cpp: In function ‘int main()’: user.cpp:40:13: warning: unused variable ‘x1’ [-Wunused-variable] int x1=n<<1; ^ user.cpp:14:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("collar.in","r",stdin); ^ user.cpp:15:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("collar.out","w",stdout); ^ user.cpp:16:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:19:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld",&v[i]); ^