#include <iostream>
#include <cmath>
#include <climits>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <functional>
#include <algorithm>
#include <sstream>
#include <map>
#include <set>
#include <utility>

#define endl '\n'
#define ALL(a)  (a).begin(),(a).end()
#define SZ(a) int((a).size())
#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(i,0,n)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define DEBUG(x) cout<<#x<<": "<<x<<endl

using namespace std;

typedef pair<int,int> P;
typedef long long int LL;

int co[3];

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	string s;
	cin>>s;
	REP(i,SZ(s)){
		if(s[i]=='t'){
			co[0]++;
		}else if(s[i]=='r'){
			co[1]++;
		}else if(s[i]=='e'){
			co[2]++;
		}
	}
	int ans=INT_MAX;
	REP(i,2) ans=min(ans,co[i]);
	ans=min(ans,co[2]/2);
	cout<<ans<<endl;
	return 0;
}