#include <bits/stdc++.h>
typedef struct {
  int flag;
  int h;
  char ch;
} SD;
SD CH[400];
int main() {
  char s[1000];
  int CN[1000];
  int P[1000];
  int count = 0;
  int i, j;
  gets(s);
  memset(CN, 0, sizeof(CN));
  memset(P, 0, sizeof(P));
  for (i = 1; i < strlen(s); i++) {
    if ('a' <= s[i] && s[i] <= 'z') {
      CH[count].ch = s[i];
      if (s[i - 1] == '/') {
        CH[count].flag = -1;
      } else
        CH[count].flag = 1;
      count++;
    }
  }
  CN[0] = CH[0].flag - 1;
  for (i = 1; i < count; i++) {
    CN[i] = CN[i - 1] + CH[i].flag;
  }
  for (i = 0; i < count; i++) {
    if (CH[i].flag == 1) CH[i].h = CN[i];
  }
  for (i = 0; i < count; i++) {
    if (CH[i].flag == -1) {
      for (j = i - 1; j >= 0; j--)
        if (CH[j].flag == 1 && P[j] == 0) {
          if (CH[i].ch == CH[j].ch) {
            CH[i].h = CH[j].h;
            P[j] = 1;
            break;
          }
        }
    }
  }
  for (i = 0; i < count; i++) {
    for (j = 1; j <= 2 * CH[i].h; j++) printf(" ");
    if (CH[i].flag == 1)
      printf("<%c>\n", CH[i].ch);
    else
      printf("<\/%c>\n", CH[i].ch);
  }
  return 0;
}
