import java.util.Scanner;

class Tree{
	private int t ;
	private int r ;
	private int e ;
	private int treeCount;
	
	public Tree(int a,int b,int c){
		this.t = a;
		this.r = b;
		this.e = c;
	}
	
	public void makeTree(){
		while(true){
			this.t -= 1;
			this.r -= 1;
			this.e -= 2;
			if(this.t >= 0 && this.r >= 0 && this.e >= 0){
				treeCount++;
			}
			else{
				break;
			}
		}
	}
	public void showTreeCount(){
		System.out.println(this.treeCount);
	}
}

public class No_279 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String sample = sc.next();
		char[] pieceOfSample = sample.toCharArray();
		int tCount = 0;
		int rCount = 0;
		int eCount = 0;
		
		for(char c:pieceOfSample){
			switch(c){
			case 't':tCount++;break;
			case 'r':rCount++;break;
			case 'e':eCount++;break;
				
			}
		}
		Tree tree = new Tree(tCount,rCount,eCount);
		tree.makeTree();
		tree.showTreeCount();
	}

}