Compilare: user.cpp: In function ‘int main()’: user.cpp:12:19: warning: format ‘%ld’ expects argument of type ‘long int*’, but argument 2 has type ‘int*’ [-Wformat=] scanf("%ld",&n); ^ user.cpp:10:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sum.in","r",stdin); ^ user.cpp:11:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("sum.out","w",stdout); ^ user.cpp:12:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld",&n); ^ user.cpp:14:54: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld",&x), printf("%lld\n",x*phi[x]*2); ^