#include <stdio.h>

int main(void) {
	int min = 100, max = 0;
	int sum = 0;
	int s[6];
	int i;
	for(i = 0;i < 6;i++){
		scanf("%d", &s[i]);
		sum += s[i];
		if(s[i] > max)max = s[i];
		if(s[i] < min)min = s[i];
	}
	printf("%.2f\n", (sum - min - max) / 4.0);

	return 0;
}