var val11;var val12;var val13;

var s;
OK=false;

function setValToNull (){
val11=0;val12=0;val13=0;val14=0;
return true}

function sum () {
return val11+val12+val13+val14;}


function check() {
if (sum()==0) {alert('Die Frage ist nicht  beantwortet !');return false};
return true}


function doOpen() {
window.location="solution.html";
return 1;
}