#include <iostream>
#include <cstdio>
#include <algorithm>
#include <string>
#include <cstring>
#include <cctype>
#include <cmath>
#include <stack>
#include <queue>
#include <vector>
#include <set>
#include <map>
#include <list>
#include <stdio.h>
#include <string.h>
#include <cstdlib>
#include <math.h>
#include <bitset>
#include <iterator>
#include <iomanip>
#include <sstream>
#define INF 2000000000
using namespace std;
int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};
#define sym cout<<"---------"<<endl;
#define ll long long
#define PL pair<long long, long long>
#define P pair<int,int>
#define mk make_pair
#define en endl
#define WHITE 0
#define BLACK 2
#define GRAY 1
#define RE return 0
#define int ll

int mp[4];

signed main(){
  string s;
  cin>>s;
  for(int i=0; i<s.size(); i++){
    if(s[i]=='t') mp[1]++;
    else if(s[i]=='r') mp[2]++;
    else if(s[i]=='e') mp[3]++;
  }
  
  int ans=0;
  while(mp[1]&&mp[2]&&mp[3]>=2){
    ans++;
    mp[1]--; mp[2]--; mp[3]-=2;
  }
  cout<<ans<<en;
}