#include <stdio.h>
int main(void){
    double ans;
    int a,b,c[100],min=-1,max=1000,minnum,maxnum,sum=0;
    for(a=0;a!=6;a++){
        scanf("%d",c[a]);
    }
        for(a=0;a!=6;a++){
            if(min>=c[a]){min=c[a];minnum=a;}
            else if(max<=c[a]){max=c[a];maxnum=a;}
    }
    c[maxnum]=-1;
    c[minnum]=-1;
        for(a=0;a!=6;a++){
        if(c[a]==-1){}
        else{sum=sum+c[a];}
    }
    ans=(double)sum/4.0;
    printf("%lf\n",ans);
}