#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

//namaega184

int main(){
	char s[1000001];scanf("%s",s);
	int tree[4]={};
	int len=strlen(s);
	for(int i=0;i<len;i++){
		if(s[i]=='t')tree[0]++;
		else if(s[i]=='r')tree[1]++;
		else if(s[i]=='e')tree[2]++;
	}
	printf("%d\n",min({tree[0],tree[1],tree[2]/2}));
	return 0;
}