import java.util.*;
import static java.lang.System.*;

import java.io.IOException;
import java.io.InputStream;

public class Main{
  public static void main(String[] args){
	  FastScanner sc = new FastScanner();
	  int N = sc.nextInt();
	  List<Double> v = new ArrayList<>();
	  for(int i=0; i<N; i++) {
		  double d = sc.nextDouble();
		  v.add(d);
	  }
	  while(v.size()> 1) {
		  Collections.sort(v);
		  double d1 = v.get(0);
		  double d2 = v.get(1);
		  v.remove(0);
		  v.remove(0);
		  double d3 = (d1 + d2) / 2;
		  v.add(d3);
	  }
	  out.println(v.get(0));
  }
}
class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte(){
        if(ptr < buflen){
            return true;
        }else{
            ptr = 0;
            try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            }
            if(buflen <= 0){
                return false;
            }
        }
        return true;
    }
    private int readByte(){
        if(hasNextByte()) return buffer[ptr++];
        else return -1;
    }
    private static boolean isPrintableChar(int c){
        return 33 <= c && c <= 126;
    }
    public boolean hasNext(){
        while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
        return hasNextByte();
    }
    public String next(){
        if(!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)){
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public long nextLong(){
        if(!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        if(b < '0' || '9' < b){
            throw new NumberFormatException();
        }
        while(true){
            if('0' <= b && b <= '9'){
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt(){
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
        return (int) nl;
    }
    public double nextDouble(){
        return Double.parseDouble(next());
    }
} import java.util.*; util.* java import static java.lang.System.*; import static java.lang.System.*; import static java.lang.System.*; import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io public class Main{
  public static void main(String[] args){
	  FastScanner sc = new FastScanner();
	  int N = sc.nextInt();
	  List<Double> v = new ArrayList<>();
	  for(int i=0; i<N; i++) {
		  double d = sc.nextDouble();
		  v.add(d);
	  }
	  while(v.size()> 1) {
		  Collections.sort(v);
		  double d1 = v.get(0);
		  double d2 = v.get(1);
		  v.remove(0);
		  v.remove(0);
		  double d3 = (d1 + d2) / 2;
		  v.add(d3);
	  }
	  out.println(v.get(0));
  }
} Main public static void main(String[] args){
	  FastScanner sc = new FastScanner();
	  int N = sc.nextInt();
	  List<Double> v = new ArrayList<>();
	  for(int i=0; i<N; i++) {
		  double d = sc.nextDouble();
		  v.add(d);
	  }
	  while(v.size()> 1) {
		  Collections.sort(v);
		  double d1 = v.get(0);
		  double d2 = v.get(1);
		  v.remove(0);
		  v.remove(0);
		  double d3 = (d1 + d2) / 2;
		  v.add(d3);
	  }
	  out.println(v.get(0));
  } main {
	  FastScanner sc = new FastScanner();
	  int N = sc.nextInt();
	  List<Double> v = new ArrayList<>();
	  for(int i=0; i<N; i++) {
		  double d = sc.nextDouble();
		  v.add(d);
	  }
	  while(v.size()> 1) {
		  Collections.sort(v);
		  double d1 = v.get(0);
		  double d2 = v.get(1);
		  v.remove(0);
		  v.remove(0);
		  double d3 = (d1 + d2) / 2;
		  v.add(d3);
	  }
	  out.println(v.get(0));
  } FastScanner sc = new FastScanner(); sc new FastScanner() int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc List<Double> v = new ArrayList<>(); v new ArrayList<>() for(int i=0; i<N; i++) {
		  double d = sc.nextDouble();
		  v.add(d);
	  } int i=0; int i=0; i 0 i<N i N i++ i++ i {
		  double d = sc.nextDouble();
		  v.add(d);
	  } {
		  double d = sc.nextDouble();
		  v.add(d);
	  } double d = sc.nextDouble(); d sc.nextDouble() sc.nextDouble sc v.add(d) v.add v d while(v.size()> 1) {
		  Collections.sort(v);
		  double d1 = v.get(0);
		  double d2 = v.get(1);
		  v.remove(0);
		  v.remove(0);
		  double d3 = (d1 + d2) / 2;
		  v.add(d3);
	  } v.size()> 1 v.size() v.size v 1 {
		  Collections.sort(v);
		  double d1 = v.get(0);
		  double d2 = v.get(1);
		  v.remove(0);
		  v.remove(0);
		  double d3 = (d1 + d2) / 2;
		  v.add(d3);
	  } Collections.sort(v) Collections.sort Collections v double d1 = v.get(0); d1 v.get(0) v.get v 0 double d2 = v.get(1); d2 v.get(1) v.get v 1 v.remove(0) v.remove v 0 v.remove(0) v.remove v 0 double d3 = (d1 + d2) / 2; d3 (d1 + d2) / 2 (d1 + d2) d1 d2 2 v.add(d3) v.add v d3 out.println(v.get(0)) out.println out v.get(0) v.get v 0 String[] args args class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte(){
        if(ptr < buflen){
            return true;
        }else{
            ptr = 0;
            try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            }
            if(buflen <= 0){
                return false;
            }
        }
        return true;
    }
    private int readByte(){
        if(hasNextByte()) return buffer[ptr++];
        else return -1;
    }
    private static boolean isPrintableChar(int c){
        return 33 <= c && c <= 126;
    }
    public boolean hasNext(){
        while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
        return hasNextByte();
    }
    public String next(){
        if(!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)){
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public long nextLong(){
        if(!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        if(b < '0' || '9' < b){
            throw new NumberFormatException();
        }
        while(true){
            if('0' <= b && b <= '9'){
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt(){
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
        return (int) nl;
    }
    public double nextDouble(){
        return Double.parseDouble(next());
    }
} FastScanner private final InputStream in = System.in; in System.in System System.in private final byte[] buffer = new byte[1024]; buffer new byte[1024] 1024 private int ptr = 0; ptr 0 private int buflen = 0; buflen 0 private boolean hasNextByte(){
        if(ptr < buflen){
            return true;
        }else{
            ptr = 0;
            try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            }
            if(buflen <= 0){
                return false;
            }
        }
        return true;
    } hasNextByte {
        if(ptr < buflen){
            return true;
        }else{
            ptr = 0;
            try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            }
            if(buflen <= 0){
                return false;
            }
        }
        return true;
    } if(ptr < buflen){
            return true;
        }else{
            ptr = 0;
            try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            }
            if(buflen <= 0){
                return false;
            }
        } ptr < buflen ptr buflen {
            return true;
        } return true; true {
            ptr = 0;
            try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            }
            if(buflen <= 0){
                return false;
            }
        } ptr = 0 ptr 0 try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            } catch(IOException e){
                e.printStackTrace();
            } IOException e {
                e.printStackTrace();
            } e.printStackTrace() e.printStackTrace e {
                buflen = in.read(buffer);
            } buflen = in.read(buffer) buflen in.read(buffer) in.read in buffer if(buflen <= 0){
                return false;
            } buflen <= 0 buflen 0 {
                return false;
            } return false; false return true; true private int readByte(){
        if(hasNextByte()) return buffer[ptr++];
        else return -1;
    } readByte {
        if(hasNextByte()) return buffer[ptr++];
        else return -1;
    } if(hasNextByte()) return buffer[ptr++];
        else return -1; hasNextByte() hasNextByte return buffer[ptr++]; buffer[ptr++] buffer ptr++ ptr return -1; -1 1 private static boolean isPrintableChar(int c){
        return 33 <= c && c <= 126;
    } isPrintableChar {
        return 33 <= c && c <= 126;
    } return 33 <= c && c <= 126; 33 <= c && c <= 126 33 <= c 33 c c <= 126 c 126 int c c public boolean hasNext(){
        while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
        return hasNextByte();
    } hasNext {
        while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
        return hasNextByte();
    } while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++; hasNextByte() && !isPrintableChar(buffer[ptr]) hasNextByte() hasNextByte !isPrintableChar(buffer[ptr]) isPrintableChar(buffer[ptr]) isPrintableChar buffer[ptr] buffer ptr ptr++ ptr return hasNextByte(); hasNextByte() hasNextByte public String next(){
        if(!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)){
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    } next {
        if(!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)){
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    } if(!hasNext()) throw new NoSuchElementException(); !hasNext() hasNext() hasNext throw new NoSuchElementException(); new NoSuchElementException() StringBuilder sb = new StringBuilder(); sb new StringBuilder() int b = readByte(); b readByte() readByte while(isPrintableChar(b)){
            sb.appendCodePoint(b);
            b = readByte();
        } isPrintableChar(b) isPrintableChar b {
            sb.appendCodePoint(b);
            b = readByte();
        } sb.appendCodePoint(b) sb.appendCodePoint sb b b = readByte() b readByte() readByte return sb.toString(); sb.toString() sb.toString sb public long nextLong(){
        if(!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        if(b < '0' || '9' < b){
            throw new NumberFormatException();
        }
        while(true){
            if('0' <= b && b <= '9'){
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    } nextLong {
        if(!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        if(b < '0' || '9' < b){
            throw new NumberFormatException();
        }
        while(true){
            if('0' <= b && b <= '9'){
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    } if(!hasNext()) throw new NoSuchElementException(); !hasNext() hasNext() hasNext throw new NoSuchElementException(); new NoSuchElementException() long n = 0; n 0 boolean minus = false; minus false int b = readByte(); b readByte() readByte if(b == '-'){
            minus = true;
            b = readByte();
        } b == '-' b '-' {
            minus = true;
            b = readByte();
        } minus = true minus true b = readByte() b readByte() readByte if(b < '0' || '9' < b){
            throw new NumberFormatException();
        } b < '0' || '9' < b b < '0' b '0' '9' < b '9' b {
            throw new NumberFormatException();
        } throw new NumberFormatException(); new NumberFormatException() while(true){
            if('0' <= b && b <= '9'){
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        } true {
            if('0' <= b && b <= '9'){
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        } if('0' <= b && b <= '9'){
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            } '0' <= b && b <= '9' '0' <= b '0' b b <= '9' b '9' {
                n *= 10;
                n += b - '0';
            } n *= 10 n 10 n += b - '0' n b - '0' b '0' if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            } b == -1 || !isPrintableChar(b) b == -1 b -1 1 !isPrintableChar(b) isPrintableChar(b) isPrintableChar b {
                return minus ? -n : n;
            } return minus ? -n : n; minus ? -n : n minus -n n n {
                throw new NumberFormatException();
            } throw new NumberFormatException(); new NumberFormatException() b = readByte() b readByte() readByte public int nextInt(){
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
        return (int) nl;
    } nextInt {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
        return (int) nl;
    } long nl = nextLong(); nl nextLong() nextLong if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException(); nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE nl < Integer.MIN_VALUE nl Integer.MIN_VALUE Integer Integer.MIN_VALUE nl > Integer.MAX_VALUE nl Integer.MAX_VALUE Integer Integer.MAX_VALUE throw new NumberFormatException(); new NumberFormatException() return (int) nl; (int) nl public double nextDouble(){
        return Double.parseDouble(next());
    } nextDouble {
        return Double.parseDouble(next());
    } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next public class Main{
  public static void main(String[] args){
	  FastScanner sc = new FastScanner();
	  int N = sc.nextInt();
	  List<Double> v = new ArrayList<>();
	  for(int i=0; i<N; i++) {
		  double d = sc.nextDouble();
		  v.add(d);
	  }
	  while(v.size()> 1) {
		  Collections.sort(v);
		  double d1 = v.get(0);
		  double d2 = v.get(1);
		  v.remove(0);
		  v.remove(0);
		  double d3 = (d1 + d2) / 2;
		  v.add(d3);
	  }
	  out.println(v.get(0));
  }
} public class Main{
  public static void main(String[] args){
	  FastScanner sc = new FastScanner();
	  int N = sc.nextInt();
	  List<Double> v = new ArrayList<>();
	  for(int i=0; i<N; i++) {
		  double d = sc.nextDouble();
		  v.add(d);
	  }
	  while(v.size()> 1) {
		  Collections.sort(v);
		  double d1 = v.get(0);
		  double d2 = v.get(1);
		  v.remove(0);
		  v.remove(0);
		  double d3 = (d1 + d2) / 2;
		  v.add(d3);
	  }
	  out.println(v.get(0));
  }
} Main
import java.util.*;
import static java.lang.System.*;

import java.io.IOException;
import java.io.InputStream;

public class Main{
  public static void main(String[] args){
	  FastScanner sc = new FastScanner();
	  int N = sc.nextInt();
	  List<Double> v = new ArrayList<>();
	  for(int i=0; i<N; i++) {
		  double d = sc.nextDouble();
		  v.add(d);
	  }
	  while(v.size()> 1) {
		  Collections.sort(v);
		  double d1 = v.get(0);
		  double d2 = v.get(1);
		  v.remove(0);
		  v.remove(0);
		  double d3 = (d1 + d2) / 2;
		  v.add(d3);
	  }
	  out.println(v.get(0));
  }
}
class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte(){
        if(ptr < buflen){
            return true;
        }else{
            ptr = 0;
            try{
                buflen = in.read(buffer);
            }catch(IOException e){
                e.printStackTrace();
            }
            if(buflen <= 0){
                return false;
            }
        }
        return true;
    }
    private int readByte(){
        if(hasNextByte()) return buffer[ptr++];
        else return -1;
    }
    private static boolean isPrintableChar(int c){
        return 33 <= c && c <= 126;
    }
    public boolean hasNext(){
        while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
        return hasNextByte();
    }
    public String next(){
        if(!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)){
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public long nextLong(){
        if(!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        if(b < '0' || '9' < b){
            throw new NumberFormatException();
        }
        while(true){
            if('0' <= b && b <= '9'){
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt(){
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
        return (int) nl;
    }
    public double nextDouble(){
        return Double.parseDouble(next());
    }
}