#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
using namespace std;

int main(){
    string s;
    cin>>s;
    int t=0,r=0,e=0;
    for(auto c:s){
        if(c=='t')t++;
        if(c=='r')r++;
        if(c=='e')e++;
    }
    e/=2;
    cout<<min({t,r,e})<<endl;
    return 0;
}