#include <iostream>
#include <string>

template <class T>
class Stack{
 private:
    T *array;
    int capacity;
    int index;

    void Expand() {
        T *newArray = new T[capacity * 4];
        for (int i = 0; i < capacity; i++) {
            newArray[i] = array[i];
        }
        delete[] array;

        capacity *= 4;
        array = newArray;
    }

 public:
    Stack() {
        array = new T[10];
        capacity = 8;
        index = 0;
    }

    void push(T n) {
        if (capacity == index) {
            Expand();
        }
        array[index++] = n;
    }

    T pop() {
        return array[--index];
    }

    T back() {
        return array[index - 1];
    }

    int size() {
        return index;
    }

    void clear() {
        delete[] array;

        capacity = 8;
        array = new T[capacity];
        index = 0;
    }

    bool empty() {
        return index == 0;
    }

    ~Stack() {
        delete[] array;
        index = 0;
        capacity = 0;
    }
};

std::string times_string(const std::string &str, int n) {
    std::string result;
    for (int i = 0; i < n; i++) {
        result += str;
    }

    return result;
}

void unpacking(const std::string &str) {
    Stack<std::string> stack;
    Stack<int> numbers;
    stack.push("");

    for (char c : str) {
        if (c == '[') {
            stack.push("");
        } else if (c == ']') {
            std::string str_times = times_string(stack.pop(), numbers.pop());
            std::string prev = stack.pop() + str_times;
            stack.push(prev);
        } else if (c >= 'a' && c <= 'z') {
            std::string prev = stack.pop() + c;
            stack.push(prev);
        } else {
            numbers.push(c - '0');
        }
    }

    std::cout << stack.pop();
}


int main() {
    std::string str;
    std::cin >> str;

    unpacking(str);

    return 0;
}