import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class No279{
	public static void main(String[] args) {
		try{
			int t = 0; int r = 0; int e = 0;
			BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
			char[] chr = br.readLine().toCharArray();
			for(int i=0; i < chr.length; i++){
				switch (chr[i]){
				case 't':
					t++;
					break;
				
				case 'r':
					r++;
					break;
					
				case 'e':
					e++;
					break;
				}
			}
			System.out.println(getMin(t,r,e));
		}
		catch(IOException e){
			e.getStackTrace();
		}
	}

	
	public static int getMin(int t, int r, int e){
		int e2 = e/2;
		int[] k ={t,r,e2};
		int min = t;
		for(int i=0; i<k.length; i++){
			if(min > k[i]){
				min =k[i];
			}
		}
		return min;
	}
}