#include<bits/stdc++.h>
using namespace std;

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