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