...}
var bootWidth = xInicial + a.offsetWidth,
bootHeight = xInicial + a.offsetHeight;
var Xs = [xInicial, (bootWidth)/2, bootHeight, (bootWidth)/2], /*[462, 591, 729, 869],*/
Ys = [(bootHeight)/2, yInicial, (bootHeight)/2, bootHeight], /*[77, 77, 77, 77],*/
count = 0, speedBoot = 20;
//...