#include<stdio.h>

int main(void){
	int s = 0,i,n,max=-1,min=101;
	for(i = 1;i <= 6;i++){
		scanf("%d",&n);
		s+=n;
		if(max < n){max = n;}
		if(min > n){min = n;}
	}
	s-=(max+min);
	printf("%d.%02d",s/4,(s*100/4)%100);
	return 0;
}