(gdb) bt
#0  0x0804a52a in skiplist<int>::insert (this=0xbfe48914, value=11) at skiplist.h:91
#1  0x08048b9b in main () at app.cpp:13
(gdb)
(gdb) p left->right
$1 = (node<int> *) 0x0
(gdb)
-111:**-F1  *gud-a.out*    Bot L81    (Debugger:run [signal])-----------------------------------------------------------------------------
    if(!marked.empty()) {
      left=marked.top();
      marked.pop();
 
      // handle corner nodes
      if(left->right != NULL) {
        if (left->isInfNeg == false) {           //! -inf
          if(left->right == NULL)
            break;
=>        while(left->right->data < value) {
              left = marked.top();
              marked.pop();
            }
        }
      }