from sys import stdin


def main():
    s = stdin.readline().rstrip()
    last_str = []
    tail = []
    for c in s:
        last_str.append(c)
        if len(last_str) < 2 or len(tail) == 0:
            if c != '=':
                tail.append(c)
            continue
        if tail[-1] == '<' and last_str[-2] == '=' and last_str[-1] == '>':
            while last_str[-1] != '<':
                last_str.pop()
            last_str.pop()
            tail.pop()
            continue
        if c != '=':
            tail.append(c)

    print(len(last_str))

    return


if __name__ == "__main__":
    main()