#include <stdio.h>


int main(void)
{
	char S;
	int i,t=0,r=0,e=0;


	
for(;;){

		if((S = getchar()) != '\n'){

			if(S=='t')

	t = t + 1;


			else if(S=='r')	r = r + 1;


			else if(S=='e')	
e = e + 1;
		}else break;
	}

	i=0;
	while(t>0&&r>0&&e>1){
		i++;
		t=t-1;	if(t==0)break;
		r=r-1;	if(r==0)break;	
		e=e-2;	if(e<=1)break;	

	}
	

	printf("%d",i);

	return 0;
}