#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <cmath>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <stdlib.h>
#include <stdio.h>
#include <bitset>
using namespace std;
#define FOR(I,A,B) for(int I = (A); I < (B); ++I)
typedef long long ll;

int main(){
  string s;
  cin >> s;
  int t = 0, r = 0, e = 0;
  FOR(i,0,s.length()){
    if(s[i]=='t') t++;
    if(s[i]=='r') r++;
    if(s[i]=='e') e++;
  }
  e /= 2;
  int ans = min(min(t, r),e);
  printf("%d\n", ans);
  return 0;
}