#include <bits/stdc++.h>
#define INF 990000000
//29
using namespace std;

int main() {
string s;
cin>>s;
int t=0;
int r=0;
int e=0;

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

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


}