! Triangle program which takes an integer as input and writes
! all even integers up to this value to the screen. Uses a 
! function.
let
    func isEven(x : Integer) : Boolean ~
      x//2 = 0;

    var i : Integer;
    var n : Integer

in
    begin
    getint(var n);
    i := 1;
    while i <= n do
        begin
        if isEven(i) then
            begin
            putint(i);
            put(' ')
            end
        else;
        i := i + 1
        end
    end