function Main(input) {
	input = input.split("\n");
	var s = input[0];
	var deg = new Object();
	var alphabet = "abcdefghijklmnopqrstuvwxyz";
	for (var i = 0; i < alphabet.length; i++){
		// console.log("%s", alphabet[i]);
		deg[alphabet[i]] = 0;

	}
	for (var i = 0; i < s.length; i++){
		deg[s[i]]  += 1;
	}
	var res = Math.min(deg["t"], deg["r"]);
	res = Math.min(res, deg["e"] / 2);
	console.log("%d", Math.floor(res));
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"));