$(function(){
 $(".hover").hover(function(){
 var cont = $(this).attr("src");
 if ((/\d\.(jpg|gif|png)/).test(cont)){
 cont = cont.replace(/(\.)(jpg|gif|png)/,"hover.$2");
 }else{
 cont = cont.replace(/(\.)(jpg|gif|png)/,"Hover.$2");
 }
 $(this).attr("src",cont)
}, function(){
 var cont = $(this).attr("src");
 cont = cont.replace(/(Hover|hover)\./,".");
 $(this).attr("src",cont)
});
});