#include <iostream>
#include <queue>
#include <vector>
#include <cstring>
using namespace std;

using ll = long long;
bool replace(std::string& str, const std::string& from, const std::string& to) {
    size_t start_pos = str.find(from);
    if(start_pos == std::string::npos)
        return false;
    str.replace(start_pos, from.length(), to);
    return true;
}
void solution(int start, int end, string& input){
    
    vector<string> tags;
    
    bool state = false;
    string current = "";
    string result = "";
    for(int i = 1; i < end; i++){
        char c = input[i];
        
        if(c == '<'){
            state = true;
            result+=current;
            current="";
        }else if(c == '>'){
            if(!state){
                current+=c;
                continue;
            }
            
            if(current[0] =='/'){
                if(i < start){
                    replace(result, "<"+tags.back()+">", "");
                    tags.pop_back();
                    current="";
                    state = false;
                    continue;
                }
                
                tags.pop_back();
            }
            else tags.push_back(current);
            
            result += "<"+current +">";
            
            current="";
            state = false;
        } else if(state || (!state && i >= start)) current+=c;
    }
    
    result+= current;
    cout << result;
    
    while(!tags.empty()){
        string tag = tags.back(); tags.pop_back();
        
        cout << "</" << tag << ">";
    }
    
}

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0);
    int start, end;
    string current;
    
    while(1){
        cin >> start >> end;
        if(start == -1) break;
        
        getline(cin, current);
        
        solution(start+1, end+1, current);
        cout << "\n";
    }

    return 0;
}
// <b></b> <a>a</a> <a></a>
// 7 17 <b></b> <a>a</a> <a></a>