P1928 外星密码

// Problem: P1928 外星密码
// Contest: Luogu
// URL: https://www.luogu.com.cn/problem/P1928
// Memory Limit: 125 MB
// Time Limit: 1000 ms
// User: Pannnn
 
#include <bits/stdc++.h>
 
using namespace std;
 
template<class T>
void printVector(const T &a) {
    cout << "[ ";
    for (size_t i = 0; i < a.size(); ++i) {
        cout << a[i] << (i == a.size() - 1 ? " " : ", ");
    }
    cout << "]" << endl;
}
 
template<class T>
using matrix2 = vector<vector<T>>;
 
template<class T>
vector<vector<T>> getMatrix2(size_t n, size_t m, T init = T()) {
    return vector<vector<T>>(n, vector<T>(m, init));
}
 
template<class T>
using matrix3 = vector<vector<vector<T>>>;
 
template<class T>
vector<vector<vector<T>>> getMatrix3(size_t x, size_t y, size_t z, T init = T()) {
    return vector<vector<vector<T>>>(x, vector<vector<T>>(y, vector<T>(z, init)));
}
 
string getRes() {
    string res;
    char c;
    int cnt;
    while (cin >> c) {
        if (c == '[') {
            cin >> cnt;
            string ts = getRes();
            while (cnt--) {
                res += ts;
            }
        } else if (c == ']') {
            return res;
        } else {
            res += c;
        }
    }
    return res;
}
 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    cout << getRes() << endl;
    return 0;
}