import java.util.ArrayDeque;
import java.util.Deque;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		char[] s = sc.next().toCharArray();
		sc.close();

		Deque<Character> que = new ArrayDeque<>();
		for (int i = 0; i < s.length; i++) {
			if (s[i] == '>') {
				int cnt = 0;
				while (!que.isEmpty()) {
					char c = que.pop();
					if (c == '=') {
						cnt++;
					} else {
						que.push(c);
						break;
					}
				}
				if (que.isEmpty() || cnt == 0) {
					for (int j = 0; j < cnt; j++) {
						que.push('=');
					}
					que.push('>');
				} else {
					char c = que.pop();
					if (c != '<') {
						que.push(c);
						for (int j = 0; j < cnt; j++) {
							que.push('=');
						}
						que.push('>');
					}
				}

			} else {
				que.push(s[i]);
			}
		}
		System.out.println(que.size());
	}
}