import java.util.Arrays;
import java.util.Scanner;
public class No0279 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		char c[] = sc.next().toCharArray();
		int tCount = 0;
		int rCount = 0;
		int eCount = 0;
		for(int i=0; i<c.length; i++){
			switch(c[i]){
			case 't':
				tCount++;
				break;
			case 'r':
				rCount++;
				break;
			case 'e':
				eCount++;
				break;
			}
		}
		eCount = eCount / 2;
		int ans[] = {tCount, rCount, eCount};
		Arrays.sort(ans);
		System.out.println(ans[0]);
	}
}