#include "bits/stdc++.h"
#define MOD 1000000007
#define INF 11234567890
#define in std::cin
#define out std::cout
#define rep(i,N) for(LL i=0;i<N;++i)
typedef long long int LL;

std::string S;
int t, r, e;

int main()
{
	in >> S;

	for (auto c : S)
	{
		if (c == 't') { ++t; }
		if (c == 'r') { ++r; }
		if (c == 'e') { ++e; }
	}
	e /= 2;

	out << std::min(t, std::min(r, e)) << std::endl;
	return 0;
}