var a = [ 'a','b','c','d','e','f','g','h','i','j','k','l','m','n','p','q','r','s','t','u','v' ]; 


function doit( s )
{
	var ii,iim = a.length;
	var t;
	
	for( ii=0 ; ii<iim ; ii++ )
	{
		t = "div_" + a[ii];
		if( t == s )
		{
			document.getElementById(t).style.display = "block";
		}
		else
		{
			document.getElementById(t).style.display = "none";
	
		}
	}

}