#include <stdio.h>
#include <string.h>
int main(){
    
    char s[1000050];
    int i,len;
    int count1 = 0;
    int count2 = 0;
    int count3 = 0;
    
    scanf("%s",s);
    
    len = strlen(s);
    
    for(i=0; i<len; i++){
        if(s[i]=='t'){
            count1++;
            continue;
        }else if(s[i]=='r'){
            count2++;
            continue;
        }else if(s[i]=='e'){
            count3++;
            continue;
        }
    }
    count3/=2;

    if(count1 <= count2 && count1 <= count3){
        printf("%d\n",count1);
    }else if(count2 <= count1 && count2 <= count3){
        printf("%d\n",count2);
    }else{
        printf("%d\n",count3);
    }    
	return 0;
}