#include<stdio.h>

int main(void){
  int i;
  int S[6];
  int max, min;
  double sum;
  scanf("%d %d %d %d %d %d", &S[0], &S[1], &S[2], &S[3], &S[4], &S[5]);
  max = min = S[0];
  sum = (double)S[0];
  for(i = 1; i < 6; i++){
    if(max < S[i]) max = S[i];
    if(min > S[i]) min = S[i];
    sum += (double)S[i];
  }
  sum = sum - (double)max - (double)min;
  printf("%.2lf\n", sum / 4);
  return 0;
}