Quick java script question

[Zelos]

What part of the code would I have to change to make the hearts fall instead of rise in this mod: https://vborg.vbsupport.ru/showthread.php?t=107521

JAVA:

var no = 9;
var speed = 15;

balloon = new Array();
balloon[0] = "http://projectjj.dk/gfx/fod_heart.gif";
balloon[1] = "http://projectjj.dk/gfx/fod_heart2.gif";
var maxballoon = 1;

var ns4up = (document.layers) ? 1 : 0;
var ie4up = (document.all) ? 1 : 0;
var dx, xp, yp;
var am, stx, sty;
var i, doc_width = 500, doc_height = 600;

if (ns4up) {
	doc_width = self.innerWidth;
	doc_height = self.innerHeight - 50;
} else if (ie4up) {
	doc_width = document.body.clientWidth;
	doc_height = document.body.clientHeight -50;
}

dx = new Array();
xp = new Array();
yp = new Array();
am = new Array();
stx = new Array();
sty = new Array();
j = maxballoon;

for (i = 0; i < no; ++ i) {
	dx[i] = 0;
	xp[i] = Math.random()*(doc_width-50);
	yp[i] = Math.random()*doc_height;
	am[i] = Math.random()*20;
	stx[i] = 0.02 + Math.random()/10;
	sty[i] = 0.7 + Math.random();
	if (ns4up) {
		if (i == 0) {
			document.write("<layer name=\"dot"+ i +"\" left=\"15\" top=\"500\" visibility=\"show\"><img src=\"" + balloon[j] + "\" border=\"0\"></layer>");
		} else {
			document.write("<layer name=\"dot"+ i +"\" left=\"15\" top=\"500\" visibility=\"show\"><img src=\"" + balloon[j] + "\" border=\"0\"></layer>");
		}
	} else if (ie4up) {
		if (i == 0) {
			document.write("<div id=\"dot"+ i +"\" style=\"POSITION: absolute; Z-INDEX: "+ i +"; VISIBILITY: visible; TOP: 500px; LEFT: 15px;\"><img src=\"" + balloon[j] + "\" border=\"0\"></div>");
		} else {
			document.write("<div id=\"dot"+ i +"\" style=\"POSITION: absolute; Z-INDEX: "+ i +"; VISIBILITY: visible; TOP: 500px; LEFT: 15px;\"><img src=\"" + balloon[j] + "\" border=\"0\"></div>");
		}
	}
	if (j == 0) {
		j = maxballoon;
	} else {
		j -= 1;
	}
}

function snowNS() {
	for (i = 0; i < no; ++ i) {
		yp[i] -= sty[i];
		if (yp[i] < 0) {
			xp[i] = Math.random()*(doc_width-am[i]-30);
			yp[i] = doc_height;
			stx[i] = 0.02 + Math.random()/10;
			sty[i] = 0.7 + Math.random();
			doc_width = self.innerWidth;
			doc_height = self.innerHeight -50;
		}
		dx[i] += stx[i];
		document.layers["dot"+i].top = yp[i];
		document.layers["dot"+i].left = xp[i] + am[i]*Math.sin(dx[i]);
	}
	setTimeout("snowNS()", speed);
}

function snowIE() {
	for (i = 0; i < no; ++ i) {
		yp[i] -= sty[i];
		if (yp[i] < 0) {
			xp[i] = Math.random()*(doc_width-am[i]-30);
			yp[i] = doc_height;
			stx[i] = 0.02 + Math.random()/10;
			sty[i] = 0.7 + Math.random();
			doc_width = document.body.clientWidth;
			doc_height = document.body.clientHeight -50;
		}
		dx[i] += stx[i];
		document.all["dot"+i].style.pixelTop = yp[i];
		document.all["dot"+i].style.pixelLeft = xp[i] + am[i]*Math.sin(dx[i]);
	}
	setTimeout("snowIE()", speed);
}

if (ns4up) {
	snowNS();
} else if (ie4up) {
	snowIE();
}