foo.cc: In function 'int main()':
foo.cc:28:5: error: 'cin' was not declared in this scope
     cin>>n;
     ^~~
foo.cc:28:5: note: suggested alternative: 'sin'
     cin>>n;
     ^~~
     sin
foo.cc:34:5: error: 'cout' was not declared in this scope
     cout<<num;
     ^~~~
foo.cc:34:5: note: suggested alternative: 'cosl'
     cout<<num;
     ^~~~
     cosl