function Main(chunk){
    // your code goes here
    chunk = chunk.trim().replace(/[^t|r|e]/g,"");
    var t_num = 0;
    var r_num = 0;
    var e_num = 0;
    for(var i in chunk){
        switch(chunk[i]){
        case 't':
            t_num++;
            break;
        case 'r':
            r_num++;
            break;
        case 'e':
            e_num++;
            break;
        }
    }
    e_num=Math.floor(e_num/2);
    console.log(Math.min(Math.min(t_num,r_num),e_num));
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));