#include <bits/stdc++.h>
#define PB push_back
#define MP make_pair
#define REP(i,n) for (int i=0;i<(n);i++)
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define ALL(a) (a).begin(),(a).end()
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
const int INF=1e9;
const int MOD=100000;
int B=1000000;
int main(){
      int ans=0,cnt[3];
      memset(cnt,0,sizeof(cnt));
      string s;
      cin>>s;
      REP(i,s.size()){
            if(s[i]=='t')cnt[0]++;
            if(s[i]=='r')cnt[1]++;
            if(s[i]=='e')cnt[2]++;
      }
      cout<<min(cnt[0],min(cnt[1],cnt[2]/2))<<endl;
}