import java.util.*;

public class Main {
	public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int elements = sc.nextInt();
        int[] value = new int[elements];
        for (int i = 0; i < elements; i++) {
            value[i] = sc.nextInt();
        }
        solve(value);
    }

    public static void solve(int[] ingredients){
        ingredients = insertionSort(ingredients);
        double result = 0;
        for(int i=0; i<ingredients.length-1; i++){
            result += ingredients[i]/Math.pow(2,i+1);
        }
        result += ingredients[ingredients.length-1]/Math.pow(2,ingredients.length-1);
        System.out.println(result);
    }

    public static int[] insertionSort(int[] a){
        int temp, ins, cmp; //temporary, insert, compare
        for(ins=1; ins<a.length; ins++){
            temp = a[ins];
            for(cmp = ins-1; cmp>=0; cmp--){
                if(temp < a[cmp]){
                    break;
                }
                a[cmp+1] = a[cmp];
            }
            a[cmp+1] = temp;
        }
        return a;
    }
} import java.util.*; util.* java public class Main {
	public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int elements = sc.nextInt();
        int[] value = new int[elements];
        for (int i = 0; i < elements; i++) {
            value[i] = sc.nextInt();
        }
        solve(value);
    }

    public static void solve(int[] ingredients){
        ingredients = insertionSort(ingredients);
        double result = 0;
        for(int i=0; i<ingredients.length-1; i++){
            result += ingredients[i]/Math.pow(2,i+1);
        }
        result += ingredients[ingredients.length-1]/Math.pow(2,ingredients.length-1);
        System.out.println(result);
    }

    public static int[] insertionSort(int[] a){
        int temp, ins, cmp; //temporary, insert, compare
        for(ins=1; ins<a.length; ins++){
            temp = a[ins];
            for(cmp = ins-1; cmp>=0; cmp--){
                if(temp < a[cmp]){
                    break;
                }
                a[cmp+1] = a[cmp];
            }
            a[cmp+1] = temp;
        }
        return a;
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int elements = sc.nextInt();
        int[] value = new int[elements];
        for (int i = 0; i < elements; i++) {
            value[i] = sc.nextInt();
        }
        solve(value);
    } main {
        Scanner sc = new Scanner(System.in);
        int elements = sc.nextInt();
        int[] value = new int[elements];
        for (int i = 0; i < elements; i++) {
            value[i] = sc.nextInt();
        }
        solve(value);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int elements = sc.nextInt(); elements sc.nextInt() sc.nextInt sc int[] value = new int[elements]; value new int[elements] elements for (int i = 0; i < elements; i++) {
            value[i] = sc.nextInt();
        } int i = 0; int i = 0; i 0 i < elements i elements i++ i++ i {
            value[i] = sc.nextInt();
        } {
            value[i] = sc.nextInt();
        } value[i] = sc.nextInt() value[i] value i sc.nextInt() sc.nextInt sc solve(value) solve value String[] args args public static void solve(int[] ingredients){
        ingredients = insertionSort(ingredients);
        double result = 0;
        for(int i=0; i<ingredients.length-1; i++){
            result += ingredients[i]/Math.pow(2,i+1);
        }
        result += ingredients[ingredients.length-1]/Math.pow(2,ingredients.length-1);
        System.out.println(result);
    } solve {
        ingredients = insertionSort(ingredients);
        double result = 0;
        for(int i=0; i<ingredients.length-1; i++){
            result += ingredients[i]/Math.pow(2,i+1);
        }
        result += ingredients[ingredients.length-1]/Math.pow(2,ingredients.length-1);
        System.out.println(result);
    } ingredients = insertionSort(ingredients) ingredients insertionSort(ingredients) insertionSort ingredients double result = 0; result 0 for(int i=0; i<ingredients.length-1; i++){
            result += ingredients[i]/Math.pow(2,i+1);
        } int i=0; int i=0; i 0 i<ingredients.length-1 i ingredients.length-1 ingredients.length ingredients ingredients.length 1 i++ i++ i {
            result += ingredients[i]/Math.pow(2,i+1);
        } {
            result += ingredients[i]/Math.pow(2,i+1);
        } result += ingredients[i]/Math.pow(2,i+1) result ingredients[i]/Math.pow(2,i+1) ingredients[i] ingredients i Math.pow(2,i+1) Math.pow Math 2 i+1 i 1 result += ingredients[ingredients.length-1]/Math.pow(2,ingredients.length-1) result ingredients[ingredients.length-1]/Math.pow(2,ingredients.length-1) ingredients[ingredients.length-1] ingredients ingredients.length-1 ingredients.length ingredients ingredients.length 1 Math.pow(2,ingredients.length-1) Math.pow Math 2 ingredients.length-1 ingredients.length ingredients ingredients.length 1 System.out.println(result) System.out.println System.out System System.out result int[] ingredients ingredients public static int[] insertionSort(int[] a){
        int temp, ins, cmp; //temporary, insert, compare
        for(ins=1; ins<a.length; ins++){
            temp = a[ins];
            for(cmp = ins-1; cmp>=0; cmp--){
                if(temp < a[cmp]){
                    break;
                }
                a[cmp+1] = a[cmp];
            }
            a[cmp+1] = temp;
        }
        return a;
    } insertionSort {
        int temp, ins, cmp; //temporary, insert, compare
        for(ins=1; ins<a.length; ins++){
            temp = a[ins];
            for(cmp = ins-1; cmp>=0; cmp--){
                if(temp < a[cmp]){
                    break;
                }
                a[cmp+1] = a[cmp];
            }
            a[cmp+1] = temp;
        }
        return a;
    } int temp temp ins ins cmp; cmp for(ins=1; ins<a.length; ins++){
            temp = a[ins];
            for(cmp = ins-1; cmp>=0; cmp--){
                if(temp < a[cmp]){
                    break;
                }
                a[cmp+1] = a[cmp];
            }
            a[cmp+1] = temp;
        } ins=1; ins=1 ins 1 ins<a.length ins a.length a a.length ins++ ins++ ins {
            temp = a[ins];
            for(cmp = ins-1; cmp>=0; cmp--){
                if(temp < a[cmp]){
                    break;
                }
                a[cmp+1] = a[cmp];
            }
            a[cmp+1] = temp;
        } {
            temp = a[ins];
            for(cmp = ins-1; cmp>=0; cmp--){
                if(temp < a[cmp]){
                    break;
                }
                a[cmp+1] = a[cmp];
            }
            a[cmp+1] = temp;
        } temp = a[ins] temp a[ins] a ins for(cmp = ins-1; cmp>=0; cmp--){
                if(temp < a[cmp]){
                    break;
                }
                a[cmp+1] = a[cmp];
            } cmp = ins-1; cmp = ins-1 cmp ins-1 ins 1 cmp>=0 cmp 0 cmp-- cmp-- cmp {
                if(temp < a[cmp]){
                    break;
                }
                a[cmp+1] = a[cmp];
            } {
                if(temp < a[cmp]){
                    break;
                }
                a[cmp+1] = a[cmp];
            } if(temp < a[cmp]){
                    break;
                } temp < a[cmp] temp a[cmp] a cmp {
                    break;
                } break; a[cmp+1] = a[cmp] a[cmp+1] a cmp+1 cmp 1 a[cmp] a cmp a[cmp+1] = temp a[cmp+1] a cmp+1 cmp 1 temp return a; a int[] a a public class Main {
	public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int elements = sc.nextInt();
        int[] value = new int[elements];
        for (int i = 0; i < elements; i++) {
            value[i] = sc.nextInt();
        }
        solve(value);
    }

    public static void solve(int[] ingredients){
        ingredients = insertionSort(ingredients);
        double result = 0;
        for(int i=0; i<ingredients.length-1; i++){
            result += ingredients[i]/Math.pow(2,i+1);
        }
        result += ingredients[ingredients.length-1]/Math.pow(2,ingredients.length-1);
        System.out.println(result);
    }

    public static int[] insertionSort(int[] a){
        int temp, ins, cmp; //temporary, insert, compare
        for(ins=1; ins<a.length; ins++){
            temp = a[ins];
            for(cmp = ins-1; cmp>=0; cmp--){
                if(temp < a[cmp]){
                    break;
                }
                a[cmp+1] = a[cmp];
            }
            a[cmp+1] = temp;
        }
        return a;
    }
} public class Main {
	public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int elements = sc.nextInt();
        int[] value = new int[elements];
        for (int i = 0; i < elements; i++) {
            value[i] = sc.nextInt();
        }
        solve(value);
    }

    public static void solve(int[] ingredients){
        ingredients = insertionSort(ingredients);
        double result = 0;
        for(int i=0; i<ingredients.length-1; i++){
            result += ingredients[i]/Math.pow(2,i+1);
        }
        result += ingredients[ingredients.length-1]/Math.pow(2,ingredients.length-1);
        System.out.println(result);
    }

    public static int[] insertionSort(int[] a){
        int temp, ins, cmp; //temporary, insert, compare
        for(ins=1; ins<a.length; ins++){
            temp = a[ins];
            for(cmp = ins-1; cmp>=0; cmp--){
                if(temp < a[cmp]){
                    break;
                }
                a[cmp+1] = a[cmp];
            }
            a[cmp+1] = temp;
        }
        return a;
    }
} Main
import java.util.*;

public class Main {
	public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int elements = sc.nextInt();
        int[] value = new int[elements];
        for (int i = 0; i < elements; i++) {
            value[i] = sc.nextInt();
        }
        solve(value);
    }

    public static void solve(int[] ingredients){
        ingredients = insertionSort(ingredients);
        double result = 0;
        for(int i=0; i<ingredients.length-1; i++){
            result += ingredients[i]/Math.pow(2,i+1);
        }
        result += ingredients[ingredients.length-1]/Math.pow(2,ingredients.length-1);
        System.out.println(result);
    }

    public static int[] insertionSort(int[] a){
        int temp, ins, cmp; //temporary, insert, compare
        for(ins=1; ins<a.length; ins++){
            temp = a[ins];
            for(cmp = ins-1; cmp>=0; cmp--){
                if(temp < a[cmp]){
                    break;
                }
                a[cmp+1] = a[cmp];
            }
            a[cmp+1] = temp;
        }
        return a;
    }
}