#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <numeric>
#include <functional>
#include <cmath>
#include <queue>
#include <stack>

#define repd(i,a,b) for (int i=(a);i<(b);i++)
#define rep(i,n) repd(i,0,n)
typedef long long ll;

using namespace std;


int inputValue(){
    int a;
    cin >> a;
    return a;
};

void inputArray(int * p, int a){
    rep(i, a){
        cin >> p[i];
    }
};

void inputVector(vector<int> * p, int a){
    rep(i, a){
        int input;
        cin >> input;
        p -> push_back(input);
    }
}

template <typename T>
void output(T a, int precision) {
    if(precision > 0){
        cout << setprecision(precision)  << a << "\n";
    }
    else{
        cout << a << "\n";
    }
}

int main(int argc, const char * argv[]) {
    
    // source code
    string str;
    cin >> str;
    
    int t = 0;
    int r = 0;
    int e = 0;
    
    rep(i, str.length()){
        if (str[i] == 't') t++;
        if (str[i] == 'r') r++;
        if (str[i] == 'e') e++;
        
    }
    e /= 2;
    
    int ret = 10000000;
    ret = min(ret, t);
    ret = min(ret, r);
    ret = min(ret, e);
    
    output(ret, 0);
    
    return 0;
}