use proconio::input;
use proconio::fastout;
use proconio::marker::Chars;

#[fastout]
#[allow(non_snake_case)]
fn main() {
    input! {
        S: Chars,
    }
    assert!(1 <= S.len() && S.len() <= 500_000);
    let mut T = Vec::new();
    let mut cnt = 0;
    for i in 0..S.len() {
        assert!(S[i] == '<' || S[i] == '>' || S[i] == '=');
        if S[i] == '=' {
            cnt += 1;
        }
        else {
            if cnt > 0 {
                T.push(('=', cnt));
                cnt = 0;
            }
            T.push((S[i], 1));
        }
    }
    if cnt > 0 {
        T.push(('=', cnt));
    }
    let mut stc = Vec::new();
    for i in 0..T.len() {
        stc.push(T[i]);
        if stc.len() < 3 {
            continue;
        }
        let n = stc.len();
        if stc[n-3].0 == '<' && stc[n-2].0 == '=' && stc[n-1].0 == '>' {
            for _ in 0..3 {
                stc.pop();
            }
        }
    }
    println!("{}", stc.iter().map(|&x| x.1).sum::<usize>());
}