#include <bits/stdc++.h>
using namespace std;

//--------------------------------------------
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define LL long long
#define INF INT_MAX/3

//--------------------------------------------
const double EPS = 1e-14;
const double PI  = acos(-1.0);

//--------------------------------------------

int main(){
  int t = 0;
  int r = 0;
  int e = 0;
  string s;

  cin >> s;

  REP (i,s.size()) {
    if (s[i] == 't') t++;
    if (s[i] == 'r') r++;
    if (s[i] == 'e') e++;
  }

  printf("%d\n",min(t,min(r,e / 2)));
}