#include <bits/stdc++.h>
#define int long long
using namespace std;
using Graph = vector<vector<int>>;

signed main(){
  string S;
  cin >> S;
  
  int t = 0;
  int r = 0;
  int e = 0;
  for( int i = 0; i < S.size(); i++ ){
    if( S.at(i) == 't' ) t++;
    else if( S.at(i) == 'r' ) r++;
    else if( S.at(i) == 'e' ) e++;
  }
  cout << min({t, r, e/2}) << endl;
  
  
}