#include<stdio.h>

int main(void){

int c;
int min=0;
int t_counter=0,r_counter=0,e_counter=0;

while( (c=getchar())!='\n' ){

if(c=='t') t_counter++;
if(c=='r') r_counter++;
if(c=='e') e_counter++;

}

min=t_counter;
if(min>r_counter) min=r_counter;
if(min>(e_counter/2)) min=e_counter/2;

printf("%d",min);

return 0;

}