/in/foo.c: In function 'main':
/in/foo.c:7:11: error: invalid type argument of unary '*' (have 'int')
  while(x1**2<=x)
           ^~
/in/foo.c:13:8: error: invalid type argument of unary '*' (have 'int')
  if(x1**2>x)
        ^~
/in/foo.c:17:1: error: expected expression before '}' token
 }
 ^