#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef pair<int,int> P;
 
const int INF = 1e9;
const int mod = 1e9+7;
const double EPS = 1e-10;
const double PI = acos(-1.0);

int main()
{
    string s;
    cin >> s;
    int t = 0,r = 0,e = 0;
    for(int i = 0; i < s.size(); i++){
        if(s[i] == 't') t++;
        if(s[i] == 'r') r++;
        if(s[i] == 'e') e++;
    }
    cout << min({t,r,e/2}) << endl;
    return 0;
}