#define _USE_MATH_DEFINES
#include<stdio.h>
#include<string>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include<iomanip>
//#include<bits/stdc++.h>


using namespace std;
int x[100008];
//int y[100008];
int z[100008];

int main(){
	
string p;
cin>>p;
int t=0,r=0,e=0;
for(int i=0;i<p.size();i++){
	if(p[i]=='t')t++;
	if(p[i]=='r')r++;
	if(p[i]=='e')e++;

}
int ans=p.size();
ans=min(ans,t);
ans=min(ans,r);
ans=min(ans,e/2);
cout<<ans<<endl;


	return 0;
}