function getRandomNumber(nMax) {
   var nRand = 0;
   var factor = 0;
   if ( nMax < 100 ) {
      factor = 100;
   }
   if ( nMax < 10 ) {
      factor = 10;
   }
   var flag = false;
   var nc = 1;
   while ( flag == false ) {
   nc=nc++;
   if ( nc > 100 ) break;
      nRand = Math.round(Math.random()*factor);
      if ( nRand < nMax ) {
         flag = true;
      }
   }
   return nRand;
}

function writeAds(pgname,nd) {
   var rarray = new Array(5);
   var nList = 3;
   var i = 0;
   // find nList different random numbers
   var nRand = getRandomNumber(nAds);
   rarray[0] = nRand;
   for ( i=1; i < nList; i++ ) {
      var flag = false;
   var nc = 1;
      while ( flag == false ) {
   nc=nc++;
   if ( nc > 100 ) break;
         var nMatch = 0;
         nRand = getRandomNumber(nAds);
         for ( var j=0; j<i; j++ ) {
            if ( nRand == rarray[j] ) {
               nMatch++;
               break;
            }
         }
         if ( nMatch == 0 ) {
            flag = true;
            rarray[i] = nRand;
         }
      }
   }
   for ( i = 0; i < nList; i++ ) {
      var str = ads[rarray[i]];
      str = str.replace('xxxdirxxx/',nd);
      document.write (str);
   }
}