#include <stdio.h>
int main(void) {
    
    int N;
    int v[50];
    int length = sizeof(v) / sizeof(int);
    
    for (int i = 0; i < length - 1; i++) {
        for (int j = length - 1; j > i; i--) {
            if (v[j] < v[j-1]) {
                int tmp = v[j];
                v[j] = v[j-1];
                v[j-1] = tmp;
            }
        }
    }
  
    float sum = (a[0] + a[1]) / 2;
    if(N = 2) {
      printf("%f", sum);
    } else {
      for(int i = 2; i < N -1; i++) {
        sum = (sum + a[i]) / 2;
      }
      printf("%f", sum);
    }
}