from sys import stdin


def main():
    s = stdin.readline().rstrip()
    last_str = []
    flag = False
    for c in s:
        last_str.append(c)
        if len(last_str) < 2:
            continue
        if not flag and last_str[-2] == '<' and last_str[-1] == '=':
            flag = True
        if flag and last_str[-1] == '<':
            flag = False
        if flag and last_str[-1] == '>':
            while last_str[-1] != '<':
                last_str.pop()
            last_str.pop()

    print(len(last_str))

    return


if __name__ == "__main__":
    main()