use std::cmp::min;
use std::io::*;

fn main() {
    let mut s: String = String::new();
    std::io::stdin().read_to_string(&mut s).ok();
    let mut itr = s.trim().split_whitespace();
    let s: Vec<char> = itr.next().unwrap().chars().collect();
    let mut map = std::collections::HashMap::new();
    for &c in s.iter() {
        let p = map.entry(c).or_insert(0);
        *p += 1;
    }

    let mut ans = 1 << 30;
    for &c in ['t', 'r', 'e'].iter() {
        let p = map.entry(c).or_insert(0);
        if c == 'e' {
            *p /= 2;
        }
        ans = min(ans, *p);
    }
    println!("{}", ans);
}