var iterator = 0;
var max = 0;

function next_slide()
{
	document.getElementById('i' + iterator).style.display = 'none';
	
	if (iterator == max-1)
		iterator = 0;
	else
		iterator++;
		
	document.getElementById('i' + iterator).style.display = 'block';
}

function prev_slide()
{
	document.getElementById('i' + iterator).style.display = 'none';
	
	if (iterator == 0)
		iterator = max-1;
	else
		iterator--;
		
	document.getElementById('i' + iterator).style.display = 'block';
}