#include<iostream>
#include<set>
#include<vector>
#include<algorithm>
#include<set>
#include<vector>
#include<string>
#include<stdlib.h>
#include<math.h>
#include<stdio.h>
using namespace std;

void probel(int x)
{
	for (int i = 0; i < x; i++)
	{
		cout << " ";
	}
}
int main()
{
	string a;
	cin >> a;
	int q = 0;
	int i = 0;
	while (i != a.size())
	{
		string block;
		if (a[i] == '<')
		{
			block += a[i];
			i++;
			while (a[i] != '>')
			{
				block += a[i];
				i++;
			}
		}
		if (block.size() == 3)
		{
			probel(q);
			cout << block << endl;
			q += 2;
		}
		else
		{
			q -= 2;
			probel(q);
			cout << block << endl;
		}
		i++;
	}
}