var currentN = 0;
var cantN = 30;
var stopped = false;
var timerN = null;

function nextN(){
		 
	if (currentN >= cantN) {
		currentN = 0;
	}
	
	document.getElementById('imgPrinc').src = imgsa[currentN]; 
	
	currentN++;
	
	if(!stopped){
		clearTimeout(timerN);
		startN();
	}
}

function prevN(){
	if (currentN == 0) {
		currentN = cantN-1;
	}else{
		currentN--;	
	}
	
	document.getElementById('imgPrinc').src = imgsa[currentN];
	
	if(!stopped){
		clearTimeout(timerN);
		startN();
	}
}

function stopstartN(){
	if (stopped) {
		document.getElementById('imgBotonN').src = "imgs/pause.gif"; 
		startN();
	} else {
		document.getElementById('imgBotonN').src = "imgs/play.gif"; 
		stopN();
	}
}

function stopN(){
	if (!stopped){
		clearTimeout(timerN);
		stopped = true;
	}
}

function startN(){
	timerN = setTimeout('nextN()',5000);
	stopped = false;
}