#include <stdio.h>
int main()
{
	int s[6];
	int i;
	int d;
	int c;
	int p;
	double dc;
	
	
	scanf("%d %d %d %d %d %d", &s[0], &s[1], &s[2], &s[3], &s[4], &s[5]);
	
	for(i=0;i<6;i++){
		for(d=5;d>i;d--){
			if(s[d-1]>s[d]){
				c=s[d];
				s[d]=s[d-1];
				s[d-1]=c;
			}
			
		}
	}
	dc=(double)(s[1]+s[2]+s[3]+s[4])/4;
	
printf("%.2f",dc);
    return 0;
}