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

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