var timer = null;


function moveBack(){
	var photoCont 	= document.getElementById("photoCont");
	var marLeft 		= photoCont.style.marginLeft;
	var step				= 2;
	var newMar			= parseFloat(marLeft)+step;
	var newMarSym		= newMar+"px";
		
	if(newMar <= 0){
		photoCont.style.marginLeft = newMarSym;
	}
}

function moveForward(maximum){
	var photoCont 	= document.getElementById("photoCont");
	var marLeft 		= photoCont.style.marginLeft;
	var step				= 2;
	var newMar			= parseFloat(marLeft)-step;
	var newMarSym		= newMar+"px";
		
	if(newMar+(102*maximum)+7 >= 720){
		photoCont.style.marginLeft = newMarSym;
	}
}

function StartForward(maximum){
  timer = setInterval('moveForward('+maximum+')', 10);
}
function StartBack(){
  timer = setInterval('moveBack()', 10);
}

function End(){
  var x = window.clearInterval(timer)
}