#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
using namespace std;

int main()
{
    string s;
    cin >> s;
    int n = s.size();

    vector<int> v(128, 0);
    for(int i=0; i<n; ++i)
        ++ v[s[i]];

    int ans = min({v['t'], v['r'], v['e']/2});
    cout << ans << endl;

    return 0;
}