function p1_onkeyup() {
    var p01=document.getElementById('cp01').value.length;
    var p04=document.getElementById('cp04').value.length;
       if( p01 ==4){
         document.getElementById('cp02').focus();
         }
         if(p04!=""){
            checkcard();
         }
         
   }
       function p2_onkeyup() {
       var p04=document.getElementById('cp04').value.length;
       if( document.getElementById('cp02').value.length==4){
         document.getElementById('cp03').focus();
         }
         if(p04!=""){
            checkcard();
         }
   }
       function p3_onkeyup() {
       var p04=document.getElementById('cp04').value.length;
       if( document.getElementById('cp03').value.length==4){
         document.getElementById('cp04').focus();
         }
         if(p04!=""){
            checkcard();
         }
   }
       function p4_onkeyup() {
       var p04=document.getElementById('cp04').value;
       if( document.getElementById('cp04').value.length==4){
         checkcard();
       }
   }