Input interval

Hi,
I have a little problem here,

The problem is how can I set the interval for the inputs?
I have setup three conditions for the inputs.

My idea is that if I press button left , it goes to condition 2, Then if I press left again, it goes to condiotion3.
However, it turn out to be no intervals, I mean I press button Left,
it just jump straight forward to condition 3, skipping condition 2.

Thanks for any help!

For an example code:

function Update () {

if (condition ==1){
if (Input.GetKeyDown (“left”))
condition =2;
}

if (condition ==2){
if (Input.GetKeyDown (“left”))
condition =3;
}

if (condition ==3){
if (Input.GetKeyDown (“left”))
condition rent =1;
}
}

the reason is within 2 frames the value will be 3 and 2 frames is really fast.... so change the code a bit like this!!

var ButtonPressedRecently=false;
function Update()
{
    if(ButtonPressedRecently==false)
    {
       ButtonPressedRecently=true;
       Invoke("ChangeCondition",0.2);                  //this value 0.2 is the time i have given give the time u need

    }

}

function ChangeCondition()
{
    condition+=1;
    if(condition==4)
       condition=1;

   ButtonPressedRecently=false;

}

Ha! it works!

Thanks for your help! flamy