import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author caoash
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        FastScanner in = new FastScanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        CAlchemist solver = new CAlchemist();
        solver.solve(1, in, out);
        out.close();
    }

    static class CAlchemist {
        public void solve(int testNumber, FastScanner br, PrintWriter pw) {
            int n = br.nextInt();
            double[] a = new double[n];
            for (int i = 0; i < n; i++) {
                a[i] = br.nextDouble();
            }
            if (n == 2) {
                pw.println((a[0] + a[1]) / 2);
                pw.close();
            }
//        ArrayList<Double> evens = new ArrayList<>(); ArrayList<Double> odds = new ArrayList<>();
//        for(int i = 0; i < n; i++){
//            if(a[i] % 2 == 0){
//                evens.add(a[i]);
//            }
//            else{
//                odds.add(a[i]);
//            }
//        }
//        Collections.sort(evens); Collections.sort(odds);
            double sum = 0;
//        if(!(evens.size() <= 1)){
//            sum += evens.get(0);
//            int size = evens.size();
//            for(int i = 1; i < size; i++){
//                sum += evens.get(i);
//                sum /= 2;
//            }
//        }
//        if(!(odds.size() <= 1)){
//            sum += odds.get(0);
//            int size = odds.size();
//            for(int i = 1; i < size; i++){
//                sum += odds.get(i);
//                sum /= 2;
//            }
//        }
            Arrays.sort(a);
            sum += a[0];
            for (int i = 1; i < a.length; i++) {
                sum += a[i];
                sum /= 2;
            }
            pw.println(sum);
        }

    }

    static class FastScanner {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private FastScanner.SpaceCharFilter filter;

        public FastScanner(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1) {
                throw new InputMismatchException();
            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public boolean isSpaceChar(int c) {
            if (filter != null) {
                return filter.isSpaceChar(c);
            }
            return isWhitespace(c);
        }

        public static boolean isWhitespace(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public double nextDouble() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E') {
                    return res * Math.pow(10, nextInt());
                }
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E') {
                        return res * Math.pow(10, nextInt());
                    }
                    if (c < '0' || c > '9') {
                        throw new InputMismatchException();
                    }
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }
}



Measured memory_bytes: 21460