#include<iostream>
#include<algorithm>
using namespace std;
int main(){
    int t=0,r=0,e=0;
    string s;
    cin >> s;
    for(int i=0;i<s.size();i++){
        if(s[i]=='t')   t++;
        else if(s[i]=='r')   r++;
        else if(s[i]=='e')   e++;
    }
    cout << min(t,min(r,e/2));
}