function slide(operator)
{
	// define minimum and maximum credit values
	var min = 2000;
	var max = 30000;
	/////////////////////////////////////////
	
	var n = document.getElementById('amount').value;
	var amount = parseInt(n);
	if (operator == 'increase' && amount < max)
		amount = amount + 1000;
	else if (operator == 'decrease' && amount > min)
		amount = amount - 1000;
	
	// update captions
	if((((amount  - 2000) / 1000) == 0) || (((amount  - 2000) / 1000) == 1)){
		document.getElementById('price1').innerHTML = '&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;';
	}
	else{
		document.getElementById('price1').innerHTML = ((amount  - 2000) / 1000) + '.000 &euro';
	}
	
	if(((amount  - 1000) / 1000) == 1 ){
		document.getElementById('price2').innerHTML = '&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;';
	}
	else{
		document.getElementById('price2').innerHTML = ((amount  - 1000) / 1000)+ '.000 &euro';
	}
	
	document.getElementById('price3').innerHTML = (amount / 1000) + '.000 &euro';
	
	if(((amount  + 1000) / 1000) == 31){
		document.getElementById('price4').innerHTML = '&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;';
	}
	else{
		document.getElementById('price4').innerHTML = ((amount  + 1000) / 1000) + '.000 &euro';
	}
	
	if((((amount  + 2000) / 1000) == 31) || (((amount  + 2000) / 1000) == 32)){
		document.getElementById('price5').innerHTML = '&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;';
	}
	else{
		document.getElementById('price5').innerHTML = ((amount  + 2000) / 1000) + '.000 &euro';
	}
	
	// update field
	document.getElementById('amount').value = amount;
}