import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.PrintWriter; import java.util.StringTokenizer; public class Main { void solve() throws IOException { String s = ns(); int[] cnt = new int[256]; for (int i = 0; i < s.length(); i++) { cnt[s.charAt(i)]++; } int ans = cnt['t']; ans = Math.min(ans, cnt['r']); ans = Math.min(ans, cnt['e'] / 2); out.println(ans); } String ns() throws IOException { while (!tok.hasMoreTokens()) { tok = new StringTokenizer(in.readLine(), " "); } return tok.nextToken(); } int ni() throws IOException { return Integer.parseInt(ns()); } long nl() throws IOException { return Long.parseLong(ns()); } double nd() throws IOException { return Double.parseDouble(ns()); } static BufferedReader in; static PrintWriter out; static StringTokenizer tok; public static void main(String[] args) throws IOException { in = new BufferedReader(new InputStreamReader(System.in)); out = new PrintWriter(System.out); tok = new StringTokenizer(""); Main main = new Main(); main.solve(); out.close(); } }