#include <bits/stdc++.h>
using namespace std;
#define REP(i, n)           for(int(i)=0;(i)<(n);++(i))

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