#include <stdio.h>

int main(void) {
	char c;
	int t,r,e;
	int num = 0;
	t = r = e = 0;
	while((c = getchar()) != EOF){
		//printf("%c",c);
		if(c == 't'){
			t++;
		}else if(c == 'r'){
			r++;
		}else if(c == 'e'){
			e++;
		}
	}
	//printf("\n");
	//printf("t = %d, r = %d, e = %d\n", t, r, e);
	
	e /= 2;
	
	num = t;
	if(num > r){
		num = r;
	}
	if(num > e){
		num = e;
	}
	printf("%d\n", num);

    return 0;
}