#include<bits/stdc++.h>
#define rep(i,a,n) for (int i = a;i < n;i++)
#define per(i,n,a) for (int i = n-1;i >= a;i--)
using namespace std;

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