//No.279 木の数え上げ
#pragma GCC optimize("O3")
#pragma GCC target("avx")
#include <bits/stdc++.h>
#define rep(i ,n) for(int i=0;i<(int)(n);++i)

using namespace std;

signed main(){
    string s; cin >> s;
    int cnt_t = 0;
    int cnt_r = 0;
    int cnt_e = 0;
    rep( i , s.size()){
        if( s[i] == 't') ++cnt_t;
        else if( s[i] == 'r') ++cnt_r;
        else if( s[i] == 'e') ++cnt_e;
    }
    cnt_e /= 2;
    int ans = (int)10e9;
    ans = min( ans , cnt_t);
    ans = min( ans , cnt_r );
    ans = min( ans , cnt_e );
    cout << ans << endl;
}