#include<stdio.h>
#include<string.h>

int main(void){
	int t=0,r=0,e=0,i,l;
	char s[1048576];
	scanf("%s",s);
	l = strlen(s);
	for(i = 0;i < l;i++){
		if(s[i] == 't'){t++;}
		if(s[i] == 'r'){r++;}
		if(s[i] == 'e'){e++;}
	}
	e/=2;
	if(t <= r && t <= e){printf("%d\n",t);}
	else if(r <= e){printf("%d\n",r);}
	else{printf("%d\n",e);}
	return 0;
}