#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <sstream>
#include <cctype>
#include <cassert>

using namespace std;

class Node{
public:
  char ch;
  int old;
  int curr;

  vector<Node> child;
  bool leaf;

};


Node root;
istringstream sin("");
char ans;
int i;

void increase(Node &curr){
  if(!curr.leaf){
    curr.curr = curr.old;
    for(int i = 0; i < curr.child.size(); ++i)
      increase(curr.child[i]);
  }
}

bool calc(Node &n){
  if(n.leaf){
    --i;
//        cout << "calcL : " << n.ch << " : " << i << endl;
    if(i == 0){
      ans = n.ch;
      return true;
    }
  }
  else{
    while(n.curr > 0){
      for(int i = 0; i < n.child.size(); ++i)
	if(calc(n.child[i]))
	  return true;
      --n.curr;
      for(int i = 0; i < n.child.size(); ++i)
	increase(n.child[i]);
    }
  }
  return false;
}

void output(Node &node){
  if(node.leaf){
    cout << node.ch;
  }
  else{
    cout << node.old << '(';
    for(int i = 0; i < node.child.size(); ++i)
      output(node.child[i]);
    cout << ')';
  }
}

void input(Node &curr){
  char ch;
  while(sin >> ch){
    if(isdigit(ch)){
      sin.putback(ch);
      int digit;
      sin >> digit;
      Node n;
      n.old = n.curr = digit;
      n.leaf = false;

      sin >> ch;
      if(ch == '('){
	input(n);
	sin >> ch;
	assert(ch == ')');
      }
      else if(isalpha(ch)){
	Node cc;
	cc.ch = ch;
	cc.leaf = true;
	n.child.push_back(cc);
      }
      else{
	assert(false);
      }
      curr.child.push_back(n);
    }
    else if(isalpha(ch)){
      Node n;
      n.ch = ch;
      n.leaf = true;
      curr.child.push_back(n);
    }
    else if(ch == ')'){
      sin.putback(ch);
      break;
    }
    else{
      assert(false);
    }
      
  }
}

int main(void){
  string word;
  while(cin >> word >> i){
    if(word == "0" && i == 0)
      break;
    ++i;
    sin.clear();
    sin.str(word);
    root.old = root.curr = 1;
    root.leaf = false;
    input(root);
//      output(root);
//      cout << endl;

    calc(root);
    if(root.curr == 0  && i > 0)
      ans = '0';
    
    cout << ans << endl;
    root.child.clear();
  }
  return 0;
}