#include<stdio.h>

int main(void){
  int i;
  char S[1000001];
  int n[4] = {}, min;
  scanf("%s", S);
  for(i = 0; S[i] != '\0'; i++){
    if(S[i] == 't') n[0]++;
    if(S[i] == 'r') n[1]++;
    if(S[i] == 'e') n[2]++;
  }
  n[2] = n[2] / 2;
  min = n[0];
  if(min > n[1]) min = n[1];
  if(min > n[2]) min = n[2];
  printf("%d\n", min);
  return 0;
}