I found three mistakes
int a = age we don't need that in c++ you can directly write int a or int age
second to take input use cin>>age;
Third if you include<<endl in double quotes then that will not work
I found two mistake You can directly use int age; and int a; as a variable Secondly make sure whatever you want to print should be enclosed with in double quatation i.e cout <<"hey";
I hope this code help you .