package yukicoder;

import java.util.Scanner;

public class Yuki279 {
	
	public static void main(String[] args) {
	
		Scanner scan = new Scanner(System.in);
		String str = scan.next();
		scan.close();
		String strArr[] = str.split("");
		int t = 0;
		int r = 0;
		int e = 0;
		for(int i = 0; i < strArr.length; i++ ) {
			switch (strArr[i]) {
			case "t":
				t += 1;
				break;
			case "r":
				r += 1;
				break;
			case "e":
				e += 1;
				break;
			}
		}
		int count = 0;
		while(t >= 1 && r >= 1 && e >= 2){
			if(t>=1 && r>=1 && e>=2){
				count++;
				t -= 1; r -= 1; e -= 2;
			}
		}
		System.out.println(count);
	}
}