#include<iostream>
#include<iomanip>
#include<cmath>
#include<string>
#include<algorithm>
#include<vector>
#include<math.h>
#include<stack>
using namespace std;
int main(void){
    string S; cin >> S;
    int cnt_t = 0, cnt_r = 0, cnt_e = 0;
    int ans = 0;
    for(int i = 0; i < S.size(); i++){
       if(S[i] == 't') cnt_t++;
       if(S[i] == 'r') cnt_r++;
       if(S[i] == 'e') cnt_e++;
    }
    ans = min(cnt_e / 2, min(cnt_t, cnt_r));
    cout << ans << endl;
    return 0;
}