#include <bits/stdc++.h>
#define FOR(i,bg,ed) for(ll i=(bg);i<(ed);i++)
#define REP(i,n) FOR(i,0,n)
#define MOD 1000000007
#define int long long
using namespace std;
typedef long long ll;
const int INF = 1e9;



signed main()
{
    string S;
    int t = 0, r = 0, e = 0;

    cin >> S;
    REP(i,S.length()) {
        if (S[i] == 't') t++;
        else if (S[i] == 'r') r++;
        else if (S[i] == 'e') e++;
    }

    cout << min(t, min(r, e / 2)) << endl;
}