#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
typedef long long ll;

int main(){
  string s;
  cin>>s;
  ll a[3];
  memset(a,0,sizeof(a));
  for(int i=0; i<s.size(); ++i){
    if(s[i]=='t') a[0]++;
    if(s[i]=='r') a[1]++;
    if(s[i]=='e') a[2]++;
  }
  ll m=0;
  m=min(a[0],a[1]);
  m=min(m,a[2]/2);
  cout<<m<<endl;
  return 0;
}