#include <stdio.h>

int main(void)
{
	char string[1000000];
	int cnt_t = 0;
	int cnt_r = 0;
	int cnt_e = 0;
	int cnt_tree = 0;

	scanf("%s", string);

	for (int i = 0; string[i] != '\0'; i++) {
		if ( string[i] == 't' ) {
			cnt_t++;		
		}
		if ( string[i] == 'r' ) {
			cnt_r++;
		}
		if ( string[i] == 'e' ) {
			cnt_e++;
		}
		if ( cnt_t >= 1 ) {
			if ( cnt_r >= 1 && cnt_e >= 2 ) {
				cnt_tree++;
				cnt_r--;
				cnt_e -= 2;
				cnt_t--;
			}
		}
	}

	printf("%d\n", cnt_tree);

	return 0;
}