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

string S;
int main(void){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    cin >> S;
    ll cntt = 0, cntr = 0, cnte = 0;
    for(char c : S){
        if(c == 't')cntt++;
        if(c == 'r')cntr++;
        if(c == 'e')cnte++;
    }
    cout << min({cntt, cntr, cnte / 2}) << endl;
    return 0;
}