#include <stdio.h>

int main(){

	long int t = 0;
	long int r = 0;
	long int e = 0;

	int c = 0;

	int count = 0;

	while ((c = getchar()) != EOF) { /* 文字の入力 */

		if (c == 't')
			t++;
		if (c == 'r')
			r++;
		if (c == 'e')
			e++;

	}

	while(t >= 1 && r >= 1 && e >= 2){
		count++;
		t--;
		r--;
		e-=2;
	}

	printf("%d", count);

	return 0;

}