package variablescope_kakunin;

public class main {
	public static void main(String[] args){
		int t_pos = 0;
		int r_pos = 0;
		int e_pos = 0;

		int tree_cnt = 0;

		String input = new java.util.Scanner(System.in).nextLine();

		while(t_pos <= input.length() || r_pos <= input.length() || e_pos <= input.length()){
			if((t_pos = input.indexOf("t", t_pos)) == -1){
				break;
			}else{
				t_pos++;
			}

			if((r_pos = input.indexOf("r", r_pos)) == -1){
				break;
			}else{
				r_pos++;
			}

			if((e_pos = input.indexOf("e", e_pos)) == -1){
				break;
			}else{
				e_pos++;
			}

			if((e_pos = input.indexOf("e", e_pos)) == -1){
				break;
			}else{
				e_pos++;
			}

			tree_cnt++;
		}

		System.out.println(tree_cnt);
	}
}