main(){
    char s[10000000];
    scanf("%s",s);
    int t=0,r=0,e=0;
    for(int count=0;s[count]!='\0';count++){
        if(s[count]=='t'){t++;}
        else if(s[count]=='r'){r++;}
        else if(s[count]=='e'){e++;}
    }
    int min=999999999;
    if(min>=t){min=t;}
        if(min>=r){min=r;}
            if(min>=(e/2)){min=(e/2);}
            printf("%d\n",min);
}