Compilare: user.cpp: In function ‘int main()’: user.cpp:2:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] int main(){freopen("fetite.in","r",stdin);freopen("fetite.out","w",stdout);long long N,i=1;scanf("%lld",&N);while(i<=N)i*=2;i/=2;printf("%lld",(N-i)*2+1);return 0;} ^ user.cpp:2:75: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] int main(){freopen("fetite.in","r",stdin);freopen("fetite.out","w",stdout);long long N,i=1;scanf("%lld",&N);while(i<=N)i*=2;i/=2;printf("%lld",(N-i)*2+1);return 0;} ^ user.cpp:2:108: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] int main(){freopen("fetite.in","r",stdin);freopen("fetite.out","w",stdout);long long N,i=1;scanf("%lld",&N);while(i<=N)i*=2;i/=2;printf("%lld",(N-i)*2+1);return 0;} ^