import java.util.Arrays;
import java.util.Scanner;

/**
 * https://atcoder.jp/contests/abc138/tasks/abc138_b
 */
public class Main {

  private static double answer(int[] vs) {
    Arrays.sort(vs);
    double prev = 0;
    for (int v : vs) {
      if (prev == 0) {
        prev = v;
        continue;
      }

      prev = (prev + v) / 2;
    }

    return prev;
  }

  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    int N = scan.nextInt();
    int[] vs = new int[N];
    for (int i = 0; i < N; i++) {
      vs[i] = scan.nextInt();
    }
    scan.close();

    System.out.println(answer(vs));
  }
} import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util public class Main {

  private static double answer(int[] vs) {
    Arrays.sort(vs);
    double prev = 0;
    for (int v : vs) {
      if (prev == 0) {
        prev = v;
        continue;
      }

      prev = (prev + v) / 2;
    }

    return prev;
  }

  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    int N = scan.nextInt();
    int[] vs = new int[N];
    for (int i = 0; i < N; i++) {
      vs[i] = scan.nextInt();
    }
    scan.close();

    System.out.println(answer(vs));
  }
} Main private static double answer(int[] vs) {
    Arrays.sort(vs);
    double prev = 0;
    for (int v : vs) {
      if (prev == 0) {
        prev = v;
        continue;
      }

      prev = (prev + v) / 2;
    }

    return prev;
  } answer {
    Arrays.sort(vs);
    double prev = 0;
    for (int v : vs) {
      if (prev == 0) {
        prev = v;
        continue;
      }

      prev = (prev + v) / 2;
    }

    return prev;
  } Arrays.sort(vs) Arrays.sort Arrays vs double prev = 0; prev 0 for (int v : vs) {
      if (prev == 0) {
        prev = v;
        continue;
      }

      prev = (prev + v) / 2;
    } int v vs {
      if (prev == 0) {
        prev = v;
        continue;
      }

      prev = (prev + v) / 2;
    } {
      if (prev == 0) {
        prev = v;
        continue;
      }

      prev = (prev + v) / 2;
    } if (prev == 0) {
        prev = v;
        continue;
      } prev == 0 prev 0 {
        prev = v;
        continue;
      } prev = v prev v continue; prev = (prev + v) / 2 prev (prev + v) / 2 (prev + v) prev v 2 return prev; prev int[] vs vs public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    int N = scan.nextInt();
    int[] vs = new int[N];
    for (int i = 0; i < N; i++) {
      vs[i] = scan.nextInt();
    }
    scan.close();

    System.out.println(answer(vs));
  } main {
    Scanner scan = new Scanner(System.in);
    int N = scan.nextInt();
    int[] vs = new int[N];
    for (int i = 0; i < N; i++) {
      vs[i] = scan.nextInt();
    }
    scan.close();

    System.out.println(answer(vs));
  } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int N = scan.nextInt(); N scan.nextInt() scan.nextInt scan int[] vs = new int[N]; vs new int[N] N for (int i = 0; i < N; i++) {
      vs[i] = scan.nextInt();
    } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
      vs[i] = scan.nextInt();
    } {
      vs[i] = scan.nextInt();
    } vs[i] = scan.nextInt() vs[i] vs i scan.nextInt() scan.nextInt scan scan.close() scan.close scan System.out.println(answer(vs)) System.out.println System.out System System.out answer(vs) answer vs String[] args args public class Main {

  private static double answer(int[] vs) {
    Arrays.sort(vs);
    double prev = 0;
    for (int v : vs) {
      if (prev == 0) {
        prev = v;
        continue;
      }

      prev = (prev + v) / 2;
    }

    return prev;
  }

  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    int N = scan.nextInt();
    int[] vs = new int[N];
    for (int i = 0; i < N; i++) {
      vs[i] = scan.nextInt();
    }
    scan.close();

    System.out.println(answer(vs));
  }
} public class Main {

  private static double answer(int[] vs) {
    Arrays.sort(vs);
    double prev = 0;
    for (int v : vs) {
      if (prev == 0) {
        prev = v;
        continue;
      }

      prev = (prev + v) / 2;
    }

    return prev;
  }

  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    int N = scan.nextInt();
    int[] vs = new int[N];
    for (int i = 0; i < N; i++) {
      vs[i] = scan.nextInt();
    }
    scan.close();

    System.out.println(answer(vs));
  }
} Main
import java.util.Arrays;
import java.util.Scanner;

/**
 * https://atcoder.jp/contests/abc138/tasks/abc138_b
 */
public class Main {

  private static double answer(int[] vs) {
    Arrays.sort(vs);
    double prev = 0;
    for (int v : vs) {
      if (prev == 0) {
        prev = v;
        continue;
      }

      prev = (prev + v) / 2;
    }

    return prev;
  }

  public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    int N = scan.nextInt();
    int[] vs = new int[N];
    for (int i = 0; i < N; i++) {
      vs[i] = scan.nextInt();
    }
    scan.close();

    System.out.println(answer(vs));
  }
}
