#include <bits/stdc++.h>
using namespace std;
int main(int argc, char** argv) {
  int h;
  string s, s1;
  while (cin >> s) {
    h = -1;
    while (s.length() > 0) {
      if (s[1] != '/') {
        s1 = s.substr(0, 3);
        s = s.substr(3, s.length() - 3);
        h++;
        for (int i = 0; i < 2 * h; i++) cout << " ";
        cout << s1 << endl;
      } else {
        s1 = s.substr(0, 4);
        s = s.substr(4, s.length() - 4);
        for (int i = 0; i < 2 * h; i++) cout << " ";
        cout << s1 << endl;
        h--;
      }
    }
  }
  return 0;
}
