#include <bits/stdc++.h>
using namespace std;
struct T {
  char a[5];
  int space;
  bool comic;
};
T xml[1001];
char a[2000];
int cnt = 0;
int main() {
  cin >> a;
  int la = strlen(a);
  for (int i = 1; i < la;) {
    if (isalpha(a[i])) {
      xml[cnt].comic = 0;
      xml[cnt].a[0] = '<';
      xml[cnt].a[1] = a[i];
      xml[cnt].a[2] = '>';
      xml[cnt].a[3] = '\0';
      if (i != 1) {
        if (!xml[cnt - 1].comic)
          xml[cnt].space = xml[cnt - 1].space + 2;
        else
          xml[cnt].space = xml[cnt - 1].space;
      }
      i += 3;
    } else {
      xml[cnt].comic = 1;
      xml[cnt].a[0] = '<';
      xml[cnt].a[1] = a[i];
      xml[cnt].a[2] = a[i + 1];
      xml[cnt].a[3] = '>';
      xml[cnt].a[4] = '\0';
      if (i != 1) {
        if (xml[cnt - 1].comic)
          xml[cnt].space = xml[cnt - 1].space - 2;
        else
          xml[cnt].space = xml[cnt - 1].space;
      }
      i += 4;
    }
    cnt++;
  }
  for (int i = 0; i < cnt; i++) {
    for (int j = 0; j < xml[i].space; j++) cout << " ";
    cout << xml[i].a << endl;
  }
  return 0;
}
