import java.io.*;
import java.util.*;
import java.util.function.*;
import java.util.stream.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int count = 0;
        Deque<Character> stack = new ArrayDeque<>();
        for (char c : sc.next().toCharArray()) {
            if (c == '<') {
                stack.push(c);
                count++;
            } else if (c == '>') {
                if (stack.size() > 0 && stack.peek() == '=' && count > 0) {
                    while (true) {
                        char x = stack.pop();
                        if (x == '<') {
                            count--;
                            break;
                        }
                    }
                } else {
                    stack.push(c);
                    count = 0;
                }
            } else {
                stack.push(c);
            }
        }
        System.out.println(stack.size());
    }
}

class Scanner {
    BufferedReader br;
    StringTokenizer st = new StringTokenizer("");

    public Scanner() {
        try {
            br = new BufferedReader(new InputStreamReader(System.in));
        } catch (Exception e) {
            
        }
    }
    
    public int nextInt() {
        return Integer.parseInt(next());
    }
    
    public long nextLong() {
        return Long.parseLong(next());
    }
    
    public double nextDouble() {
        return Double.parseDouble(next());
    }
    
    public String next() {
        try {
            while (!st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            return st.nextToken();
        }
    }
    
}