#include <bits/stdc++.h>
#define FOR(i,a,b) for(int i = (a); i < (b); ++i)
#define REP(i,n) FOR(i,0,n)
#define SZ(n) (int)(n).size()
#define ALL(n) (n).begin(), (n).end()
using namespace std;
typedef long long LL;
typedef vector<int> VI;

int main() {
	string s;
	cin >> s;
	int t = 0, r = 0, e = 0;
	REP(i, SZ(s)) if (s[i] == 't') t++;
	REP(i, SZ(s)) if (s[i] == 'r') r++;
	REP(i, SZ(s)) if (s[i] == 'e') e++;
	cout << min(t, min(r, e / 2)) << endl;
	return 0;
}