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