#include <stdio.h>

int main(void){
    char p[10000000];
    int count[3] = {0,0,0};
    scanf("%s",p);
    char *ptr = &p[0];
    int i = 0;
    while(*(ptr+i) != '\0'){
        if(*(ptr+i) == 't'){
            count[0]++;
        }
        if(*(ptr+i) == 'r'){
            count[1]++;
        }
        if(*(ptr+i) == 'e'){
            count[2]++;
        }
        i++;
    }
    count[2] = count[2]/2;
    int max = count[0] , min = count[0];
    for(i = 0;i < 3;i++){
        if(min > count[i]){
            min = count[i];
        }
    }
    
    printf("%d\n",min);
   
    return 0;
}