/in/foo.c: In function 'main':
/in/foo.c:6:2: error: 'class' undeclared (first use in this function)
  class int AVG;
  ^~~~~
/in/foo.c:6:2: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:6:8: error: expected ';' before 'int'
  class int AVG;
        ^~~
/in/foo.c:7:8: error: expected ';' before 'int'
  class int MAX;
        ^~~
/in/foo.c:8:8: error: expected ';' before 'int'
  class int MIN;
        ^~~
/in/foo.c:5:6: warning: unused variable 'a' [-Wunused-variable]
 {int a=10;
      ^