#define _USE_MATH_DEFINES
#include<stdio.h>
#include<string>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include<iomanip>
using namespace std;

int main(){
	string p;
	cin>>p;
	int a=0,b=0,c=0;
	for(int i=0;i<p.size();i++){
		if(p[i]=='t')a++;
		if(p[i]=='r')b++;
		if(p[i]=='e')c++;
	}
	c/=2;
	int ans=a;
	ans=min(ans,b);
	ans=min(ans,c);
	cout<<ans<<endl;
	return 0;
}