use std::collections::HashMap;

fn main(){
    let mut sc = Scanner::new();
    while let Ok(s) = sc.wrapped::<String>() {
        let mut h:HashMap<char,i32> = HashMap::new();
        h.insert('t', 0);
        h.insert('r', 0);
        h.insert('e', 0);
        for c in s.chars() {
            match h.get(&c).cloned() {
                Some(k) => { h.insert(c, k+1); },
                None => { h.insert(c, 1); },
            }
        };
        let x = std::cmp::min(h.get(&'t').unwrap(), h.get(&'r').unwrap());
        let x = std::cmp::min(x.clone(), h.get(&'e').unwrap()/2);
        println!("{}",x);
    }
}

#[allow(dead_code)]
struct Scanner {
    token_buffer : Vec<String>,
    index : usize,
}

#[allow(dead_code)]
impl Scanner {
    fn new() -> Scanner {
        Scanner { token_buffer: vec![], index: 0 }
    }

    fn wrapped<T>(&mut self) -> Result<T,&str> where T: std::str::FromStr {
        let s = try!(self.fetch_token());
        let t = try!(s.parse::<T>().map_err(|_| "Parse error"));
        Ok(t)
    }
    fn next<T>(&mut self) -> T where T: std::str::FromStr {
        self.wrapped::<T>().unwrap()
    }

    fn fetch_token(&mut self) -> Result<&String,&str> {
        while self.index >= self.token_buffer.len() {
            let mut st = String::new();
            while st.trim() == "" {
                match std::io::stdin().read_line(&mut st) {
                    Ok(l) if l > 0 => continue,
                    Ok(_)  => return Err("End of file"),
                    Err(_) => return Err("Failed to read line"),
                }
            }
            self.token_buffer = st.split_whitespace()
                .map(|x| x.to_string())
                .collect();
            self.index = 0;
        }

        self.index += 1;
        Ok(&self.token_buffer[self.index - 1])
    }
}