/in/foo.c: In function 'main':
/in/foo.c:9:2: error: expected ';' before 'while'
  while(1)
  ^~~~~
/in/foo.c:7:6: warning: unused variable 'sign' [-Wunused-variable]
  int sign=1;
      ^~~~
/in/foo.c:6:6: warning: unused variable 'i' [-Wunused-variable]
  int i=0,a;
      ^
/in/foo.c:5:9: warning: unused variable 'pi' [-Wunused-variable]
  double pi=0;
         ^~