function Change_Illustration(qteCount) {
        
    if(actElementID == qteCount) {
        actElementID = 0;       
    }
    
    for(var i=0; i < qteCount; i++) {   
        var id = 'illu'+i;
        if(i == actElementID) {
            document.getElementById(id).style.display = "block";    
        }
        else {
            document.getElementById(id).style.display = "none"; 
        }
    }
    
    actElementID++;
}