fn main() {
    let s = input_line_vch();
    let mut count = vec![0, 0, 0];

    for ch in &s {
        match ch {
            't' => count[0] += 1,
            'r' => count[1] += 1,
            'e' => count[2] += 1,
            _ => (),
        }
    }
    count[2] /= 2;

    println!("{}", count.iter().min().unwrap());
}

#[allow(unused)]
fn input_a_value<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

#[allow(unused)]
fn input_line<T: std::str::FromStr>() -> Vec<T> {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}

#[allow(unused)]
fn input_matrix_num<T: std::str::FromStr>(n_lines: usize) -> Vec<Vec<T>> {
    (0..n_lines).map(|_| input_line()).collect()
}

#[allow(unused)]
fn input_line_string() -> String {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().to_string()
}

#[allow(unused)]
fn input_line_vch() -> Vec<char> {
    input_line_string().chars().collect()
}

#[allow(unused)]
fn input_matrix_ch(n_lines: usize) -> Vec<Vec<char>> {
    (0..n_lines).map(|_| input_line_vch()).collect()
}