fn main() {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    let s = s.trim();
    
    println!("{}", 
        std::cmp::min(
            std::cmp::min(
                s.match_indices("t").count(),
                s.match_indices("r").count()
            ),
            s.match_indices("e").count() / 2
        )
    );    
}