foo.cc: In function 'int main()':
foo.cc:12:9: error: 'sqrt' was not declared in this scope
   int n=sqrt(x);
         ^~~~
foo.cc:12:9: note: suggested alternative: 'short'
   int n=sqrt(x);
         ^~~~
         short
foo.cc:27:2: error: 'cout' was not declared in this scope
  cout<<cnt<<endl;
  ^~~~
foo.cc:27:2: note: suggested alternative: 'cnt'
  cout<<cnt<<endl;
  ^~~~
  cnt
foo.cc:27:13: error: 'endl' was not declared in this scope
  cout<<cnt<<endl;
             ^~~~
foo.cc:27:13: note: suggested alternative: 'enum'
  cout<<cnt<<endl;
             ^~~~
             enum