#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
int gcd(int a,int b){return b?gcd(b,a%b):a;}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    string s;
    int t_c,r_c,e_c;
    t_c=r_c=e_c=0;
    cin >> s;
    rep(i,s.length()) {
        switch (s[i]) {
            case 't':
                t_c++;
                break;
            case 'r':
                r_c++;
                break;
            case 'e':
                e_c++;
                break;
        }
    }
    if (t_c>r_c) t_c=r_c;
    if (t_c>e_c/2) t_c=e_c/2;
    cout << t_c << endl;
    return 0;
}