using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static string InputPattern = "InputX";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("<=<<==>=><>");
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add(">=<=<>=>=<");
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();
        string S = InputList[0];
        List<RunLen.RunLenInfo> RunLenList = RunLen.DeriveRunLenInfoList(S);

        var InsLinkedList = new LinkedList<RunLen.RunLenInfo>();
        foreach (RunLen.RunLenInfo EachRunLen in RunLenList) {
            if (EachRunLen.AppearChar == '=') {
                InsLinkedList.AddLast(EachRunLen);
            }
            else {
                for (int I = 1; I <= EachRunLen.RunLen; I++) {
                    RunLen.RunLenInfo WillAdd;
                    WillAdd.AppearChar = EachRunLen.AppearChar;
                    WillAdd.RunLen = 1;
                    InsLinkedList.AddLast(WillAdd);
                }
            }

            while (true) {
                if (InsLinkedList.Count >= 3) {
                    RunLen.RunLenInfo Last2 = InsLinkedList.Last.Value;
                    RunLen.RunLenInfo Last1 = InsLinkedList.Last.Previous.Value;
                    RunLen.RunLenInfo Last0 = InsLinkedList.Last.Previous.Previous.Value;
                    if (Last0.AppearChar == '<' &&
                        Last1.AppearChar == '=' &&
                        Last2.AppearChar == '>') {
                        InsLinkedList.RemoveLast();
                        InsLinkedList.RemoveLast();
                        InsLinkedList.RemoveLast();
                        continue;
                    }
                }
                break;
            }
        }
        long Answer = InsLinkedList.Sum(pX => pX.RunLen);
        Console.WriteLine(Answer);
    }
}

#region RunLen
// ランレングス圧縮(文字列)
internal class RunLen
{
    // ランレングス圧縮情報
    internal struct RunLenInfo
    {
        internal char AppearChar;
        internal int RunLen;
    }

    // ランレングス圧縮結果を返す
    internal static List<RunLenInfo> DeriveRunLenInfoList(string pBaseStr)
    {
        var WillReturn = new List<RunLenInfo>();

        int StrUB = pBaseStr.Length - 1;
        char PrevChar = pBaseStr[0];
        int StrLen = 0;
        for (int I = 0; I <= StrUB; I++) {
            if (pBaseStr[I] != PrevChar) {
                RunLenInfo WillAdd;
                WillAdd.AppearChar = PrevChar;
                WillAdd.RunLen = StrLen;
                WillReturn.Add(WillAdd);
                StrLen = 0;
                PrevChar = pBaseStr[I];
            }
            StrLen++;

            if (I == StrUB) {
                RunLenInfo WillAdd;
                WillAdd.AppearChar = pBaseStr[I];
                WillAdd.RunLen = StrLen;
                WillReturn.Add(WillAdd);
            }
        }
        return WillReturn;
    }
}
#endregion