#include <iostream>
#include <algorithm>
#include <string>
#include <cstring>
using namespace std;

#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)
#define SQR(X) ((X)*(X))

typedef long long ll;
typedef unsigned long long ull;
typedef long double lb;
/* ここからが本編 */

int main(void)
{
   int i,j;
   int k;
   char s[1000006];
   int t = 0;
   int r = 0;
   int e = 0;
   for(i=0;cin >> s[i];i++) {
      if(s[i] == 't') t++;
      else if(s[i] == 'r') r++;
      else if(s[i] == 'e') e++;
   }
   cout << min(t,min(r,e/2)) << endl;
   return 0;
}