#include <bits/stdc++.h>
#define rep(i,l,n) for(int i=l;i<n;i++)
#define rer(i,l,n) for(int i=l;i<=n;i++)
#define all(a) a.begin(),a.end()
#define o(a) cout<<a<<endl
#define pb(a) push_back(a)
#define mk(a,b) make_pair(a,b)
#define fi first
#define se second
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pii;

int main(){
	string s;
	cin>>s;
	int t=0,r=0,e=0,ans=0;
	rep(i,0,s.size()){
		if(s[i]=='t') t++;
		if(s[i]=='r') r++;
		if(s[i]=='e') e++;
	}
	ans=min(t,min(r,e/2));
	o(ans);
}