Compilare: main.cpp: In function 'int main()': main.cpp:2:62: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] using namespace std;int main(){freopen("fetite.in","r",stdin);freopen("fetite.out","w",stdout);unsigned long long N,R,I=2;for(cin>>N;I<=N;I*=2)R=(N-I)*2+1;cout<<R;} ^ main.cpp:2:95: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] using namespace std;int main(){freopen("fetite.in","r",stdin);freopen("fetite.out","w",stdout);unsigned long long N,R,I=2;for(cin>>N;I<=N;I*=2)R=(N-I)*2+1;cout<<R;} ^