#include <stdio.h>
#include <string>
#include <algorithm>
int main(){
    //input
    char S[1000001];
    scanf("%s",S);

    //count 't','r','e'
    int count_t = 0;
    int count_r = 0;
    int count_e = 0;
    for (int i = 0;i < 1000001;i++){
        if (S[i] != '\0'){
            if (S[i] == 't') count_t++;
            if (S[i] == 'r') count_r++;
            if (S[i] == 'e') count_e++;
        }else{
            break;
        }
    }

    //count 'tr','ee','tree'
    int count_tr = std::min(count_t,count_r);
    int count_ee = (count_e-count_e%2)/2;
    int count_tree = std::min(count_tr,count_ee);

    //output
    printf("%d\n",count_tree);
    return 0;
}