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