#include <stdio.h>
#include <algorithm>
int main(){
    //input
    int S[6];
    for (int i = 0;i < 6;i++){
        scanf("%d",&S[i]);
    }

    //sort array S
    std::sort(S,S+6);

    //output
    printf("%.2f\n",0.25*(S[1]+S[2]+S[3]+S[4]));
    return 0;
}