#include <bits/stdc++.h>
using namespace std;

int main() {
  string s;
  cin>>s;
  int t=0,r=0,e=0;
  for(char c:s){
    if(c=='t') t++;
    if(c=='r') r++;
    if(c=='e') e++;
  }
  cout<<min({e/2,t,r})<<endl;
  return 0;
}