function stredni(x) {
var x,y;
if(x==1) {x=700; y=500} else {x=500; y=700}
window.open("a", "stredni", "toolbar=no,menubar=no,location=no,directories=no, scrollbars=yes,resizable=yes,width="+x+",height="+y+",status=no,top=10,left=10");
}