#include<iostream>
#include<iomanip>
#include<algorithm>
#include<vector>
#include<string>
#include<math.h>

#define REP(i,a,b) for(int i=(a);i<(b);i++)
#define rep(i,n) for(int i=0;i<(n);i++)
#define ALL(i) (i).begin(),(i).end()
#define rALL(i) (i).rbegin(),(i).rend()
#define debug(x) cout<<#x<<": "<<x<<endl
#define pi M_PI

typedef long long ll;
typedef unsigned long long ull;

using namespace std;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
/*-------- code --------*/
    string s;
    int tc = 0, rc = 0, ec = 0;
    int ans = 0;
    cin >> s;
    rep(i,s.length()){
        if(s[i] == 't')tc++;
        else if(s[i] == 'r')rc++;
        else if(s[i] == 'e')ec++;
    }

    while(tc > 0 && rc > 0 && ec > 1){
        ans++;
        tc--;
        rc--;
        ec -= 2;
    }

    cout << ans << endl;
}