#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  cin >> s;
  int cur = 0;
  string h = "";
  while (cur < s.size()) {
    if (s[cur + 1] != '/') {
      cout << h << s[cur] << s[cur + 1] << s[cur + 2] << endl;
      h += "  ";
      cur += 3;
    } else {
      h = h.substr(0, h.size() - 2);
      cout << h << s[cur] << s[cur + 1] << s[cur + 2] << s[cur + 3] << endl;
      cur += 4;
    }
  }
}
