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

class range {private: struct I{int x;int operator*(){return x;}bool operator!=(I& lhs){return x<lhs.x;}void operator++(){++x;}};I i,n;
public:range(int n):i({0}),n({n}){}range(int i,int n):i({i}),n({n}){}I& begin(){return i;}I& end(){return n;}};

int main(void) {
  string s; cin >> s;
  map<char, int> kort;
  for(char ch : s) { kort[ch]++; }
  int res = min({kort['t'], kort['r'], kort['e']/2});
  printf("%d\n", res);
  return 0;
}