#include<iostream>
#include<string>
#include<algorithm>

using namespace std;

int main(){

	string S;
	int t=0,r=0,e=0;

	cin>>S;

	for(int i=0;i<S.size();i++){
		if(S[i]=='t') t++;
		if(S[i]=='e') e++;
		if(S[i]=='r') r++;
	}

	cout<<min(min(t,r),e/2)<<endl;
}