import java.util.*;

class No0279{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		String s = sc.next();
		int cnt_t = 0;
		int cnt_r = 0;
		int cnt_e = 0;
		int cnt = 0;
		for(int i = 0; i < s.length(); i++){
			switch(s.charAt(i)){
				case 't': cnt_t++; break;
				case 'r': cnt_r++; break;
				case 'e': cnt_e++; break;
			}
		}

		while(true){
			if(cnt_t > 0 && cnt_r > 0 && cnt_e > 1){
				cnt++;
				cnt_t--;
				cnt_r--;
				cnt_e -= 2;
			}else{
				break;
			}
		}
		System.out.println(cnt);
	}
}