public void push(string s, int a)//для генерации
 {
     NodeGen buf = new NodeGen(s,a);
     buf.nextGen = headGen;
     headGen = buf;
 }
 public NodeGen popGen()//для генерации
 {
     NodeGen buf = headGen;
     headGen = headGen.nextGen;
     return buf;
 }
 public Stack()
 {
     head = null;
     headGen = null;
 }