using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var s = ReadLine();
        var ans = s.Length;
        var st = new Stack<char>();
        foreach (var c in s)
        {
            if (c == '>')
            {
                var count = 1;
                while (st.Count > 0 && st.Peek() == '=')
                {
                    ++count;
                    st.Pop();
                }
                if (count > 1 && st.Count > 0 && st.Peek() == '<')
                {
                    ans -= count + 1;
                    st.Pop();
                }
                else
                {
                    st = new Stack<char>();
                }
            }
            else st.Push(c);
        }
        WriteLine(ans);
    }
}