#include <bits/stdc++.h>
using namespace std;
char S[1000001];
int main() {
    scanf("%s",S);
    int t=0,r=0,e=0;
    for(int i=0;S[i]!='\0';i++) {
        if(S[i]=='t') t++;
        else if(S[i]=='r') r++;
        else if(S[i]=='e') e++;
    }
    printf("%d\n",min(t,min(r,e/2)));
}