use proconio::input;
use std::cmp::min;
use std::collections::HashMap;

fn main() {
	input! {
		s: String,
	}

    let mut hash_map = HashMap::new();

    for c in s.chars() {
        *hash_map.entry(c).or_insert(0) += 1;
    }

    let t = hash_map.get(&'t').unwrap_or(&0);
    let r = hash_map.get(&'r').unwrap_or(&0);
    let e = hash_map.get(&'e').unwrap_or(&0);

    let ans = min(*t, min(*r, e/2));

	println!("{ans}");
}