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

#[fastout]
#[allow(non_snake_case)]
fn main() {
    input! {
        S: Chars,
    }
    let N = S.len();
    let mut stk = Vec::new();
    let mut cnt = 0;
    for i in 0..N {
        if S[i] == '<' {
            stk.push(S[i]);
            cnt += 1;
        }
        else if S[i] == '=' {
            stk.push(S[i]);
        }
        else {
            let len = stk.len();
            if cnt == 0 || stk[len-1] == '<' {
                stk.push(S[i]);
                cnt = 0;
            }
            else {
                let mut x = stk.pop().unwrap();
                while x == '=' {
                    x = stk.pop().unwrap();
                }
                cnt -= 1;
            }
        }
    }
    println!("{}", stk.len());
}