var number = Math.floor(Math.random()*5)+1;
var timer1 = setTimeout("changeslide()",1000)
function changeslide()
{
 number++; if(number>5) number=1;
 var plik = "<img src=\"slajdy/slajd"+number+".png\" />";
 document.getElementById("slider").innerHTML = plik;
 timer1


}