var i, numPics;
i = 1;
numPics = 7;

document.onkeyup = KeyCheck;

function next()
{
	if(i < numPics)
	{
		i = i + 1;	
		document.getElementById("main").src="images/seesaw" + i + ".jpg";
		document.getElementById("prev").innerHTML = "<a href='javascript:prev()'><- Previous Image</a>";
		if(i == numPics)
			document.getElementById("next").innerHTML = "Next Image ->";
	}
}

function prev()
{
	if(i > 1)
	{
		i = i - 1;	
		document.getElementById("main").src="images/seesaw" + i + ".jpg";
		document.getElementById("next").innerHTML = "<a href='javascript:next()'>Next Image -></a>";
		if(i == 1)
			document.getElementById("prev").innerHTML = "<- Previous Image"
	}
}

//firefox keyboard picture change
function KeyCheck(e)
{
	var KeyID = (window.event) ? event.keyCode : e.keyCode;
	switch(KeyID)
	{
		case 37:
			prev();
			break;
		case 39:
			next();
			break;
	}
}