#include <stdio.h>

int main(){
  char c;
  int t=0, r=0, e=0, m;
  while((c = getchar()) != '\n'){
    switch(c){
    case 't': t++; break;
    case 'r': r++; break;
    case 'e': e++; break;
    }
  }
  m = t < r ? t : r;
  m = e/2 < m ? e/2 : m;
  printf("%d\n", m);
  return 0;
}