#include<iostream>
#include<cstdio>
#include<vector>
#include<queue>

#include<map>
#include<set>
#include<string>
#include<algorithm>
#include<functional>
using namespace std;
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define INF 1<<30
#define MP make_pair
#define mp make_pair
#define pb push_back
#define PB push_back
#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define ll long long
#define ull unsigned long long
int cnt[26];
int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	string s;cin>>s;
	int n=s.size();
	REP(i,n){
		cnt[s[i]-'a']++;
	}
	int ans = min(cnt['t'-'a'], min(cnt['r'-'a'], cnt['e'-'a']/2) );
	cout<<ans<<endl;

}