#include <bits/stdc++.h>
using namespace std;
double EPS = 1e-9;
int INF = 2000000000;
long long INFF = 8000000000000000000LL;
double PI = acos(-1);
string IntToString(int a) {
  char x[100];
  sprintf(x, "%d", a);
  string s = x;
  return s;
}
int StringToInt(string a) {
  char x[100];
  strcpy(x, a.c_str());
  int res;
  sscanf(x, "%d", &res);
  return res;
}
int spaces = 0;
char c[5];
int main() {
  while (scanf("%c", &c[0]) != EOF && c[0] != '\n') {
    scanf("%c%c", &c[1], &c[2]);
    if (c[2] == '>') {
      spaces += 2;
      for (int(i) = (1); (i) <= (spaces - 2); (i)++) printf(" ");
      for (int(i) = (0); (i) <= (2); (i)++) printf("%c", c[i]);
      puts("");
    } else {
      scanf("%c", &c[3]);
      spaces -= 2;
      for (int(i) = (1); (i) <= (spaces); (i)++) printf(" ");
      for (int(i) = (0); (i) <= (3); (i)++) printf("%c", c[i]);
      puts("");
    }
  }
  return 0;
}
