function ad( ) {
var r ;
var xx = new Array( ) ;

xx.push( '<iframe src="jump1.html" border="0" width="336" height="300" scrolling="no" margin="0" frameborder="0"></iframe>' ) ;
xx.push( '<iframe src="jump2.html" border="0" width="336" height="300" scrolling="no" margin="0" frameborder="0"></iframe>' ) ;
xx.push( '<iframe src="jump3.html" border="0" width="336" height="300" scrolling="no" margin="0" frameborder="0"></iframe>' ) ;
xx.push( '<iframe src="jump4.html" border="0" width="336" height="300" scrolling="no" margin="0" frameborder="0"></iframe>' ) ;

r = Math.floor( Math.random( ) * xx.length ) ;
document.write( xx[r] ) ;
}