#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <math.h>
#include <cmath>
#include <limits.h>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <functional>
#include <stdio.h>
using namespace std;

long long MOD = 1000000007;

int main() {
    
    int alphabet[26] = {0};
    string S;
    cin >> S;
    
    for ( auto& s : S ) {
        alphabet[ s - 'a' ]++;
    }
    
    cout << min( alphabet[ 'e' - 'a' ]/2, min( alphabet[ 't' - 'a' ],  alphabet[ 'r' - 'a' ] ) ) << endl;
    
    
    return 0;
}