uses
  SysUtils;
var
  a : array[0..10000] of longint;
  n, m, i, x, y : longint;
begin
  readln(n);
  if n = 1 then
    writeln(1)
  else if n mod 4 = 0 then
    writeln(0)
  else if (n mod 4 = 3) or (n = 25) or (n = 5) then
    writeln(2)
  else
    writeln(1);
  readln;
end.

i don't think it correct.
how about   45   65 ?    85 ? 105 ?

your code isn't always correct .
you must use  :
 if (n mod 4 = 1 and n mod 5 = 0) writeln(2)
this is correct...