#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define rng(a) a.begin(),a.end()
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
#define dame { puts("-1"); return 0;}
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    string s; cin >> s;
    int cnt[3] = {};
    rep(i,s.size()){
        if(s[i] == 't')cnt[0]++;
        if(s[i] == 'r')cnt[1]++;
        if(s[i] == 'e')cnt[2]++;
    }
    int ans = min(min(cnt[0], cnt[1]), cnt[2]/2);

    cout << ans << endl;
    return 0;
}