#include <bits/stdc++.h>
using namespace std;
int main(){
	string s;	cin>>s;
	int t=0,r=0,e=0;
	for(int i=0;i<(int)s.size();i++){
		if(s[i]=='t')	t++;
		else if(s[i]=='r')	r++;
		else if(s[i]=='e')	e++;
	}
	e/=2;
	int ans=min(t,min(r,e));
	cout<<ans<<endl;
	return 0;
}