import java.io.PrintWriter;
import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner stdin = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		
		int N = Integer.parseInt(stdin.next());
		double v[] = new double[N];

		for(int i=0;i<N;i++) {
			v[i] = Integer.parseInt(stdin.next());
		}
		for(int i=0;i<N-1;i++) {
			for(int j=i+1;j<N;j++) {
				if(v[i] > v[j]) {
					double max = v[i];
					v[i] = v[j];
					v[j] = max;
				}
			}
		}
		
		for(int i=0;i<N-1;i++) {
			v[i+1] = (v[i]+v[i+1])/2;
		}
		
		out.println(v[N-1]);

		out.flush();
	}
	
} import java.io.PrintWriter; PrintWriter java.io import java.util.*; util.* java public class Main {
	public static void main(String[] args) {
		Scanner stdin = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		
		int N = Integer.parseInt(stdin.next());
		double v[] = new double[N];

		for(int i=0;i<N;i++) {
			v[i] = Integer.parseInt(stdin.next());
		}
		for(int i=0;i<N-1;i++) {
			for(int j=i+1;j<N;j++) {
				if(v[i] > v[j]) {
					double max = v[i];
					v[i] = v[j];
					v[j] = max;
				}
			}
		}
		
		for(int i=0;i<N-1;i++) {
			v[i+1] = (v[i]+v[i+1])/2;
		}
		
		out.println(v[N-1]);

		out.flush();
	}
	
} Main public static void main(String[] args) {
		Scanner stdin = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		
		int N = Integer.parseInt(stdin.next());
		double v[] = new double[N];

		for(int i=0;i<N;i++) {
			v[i] = Integer.parseInt(stdin.next());
		}
		for(int i=0;i<N-1;i++) {
			for(int j=i+1;j<N;j++) {
				if(v[i] > v[j]) {
					double max = v[i];
					v[i] = v[j];
					v[j] = max;
				}
			}
		}
		
		for(int i=0;i<N-1;i++) {
			v[i+1] = (v[i]+v[i+1])/2;
		}
		
		out.println(v[N-1]);

		out.flush();
	} main {
		Scanner stdin = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		
		int N = Integer.parseInt(stdin.next());
		double v[] = new double[N];

		for(int i=0;i<N;i++) {
			v[i] = Integer.parseInt(stdin.next());
		}
		for(int i=0;i<N-1;i++) {
			for(int j=i+1;j<N;j++) {
				if(v[i] > v[j]) {
					double max = v[i];
					v[i] = v[j];
					v[j] = max;
				}
			}
		}
		
		for(int i=0;i<N-1;i++) {
			v[i+1] = (v[i]+v[i+1])/2;
		}
		
		out.println(v[N-1]);

		out.flush();
	} Scanner stdin = new Scanner(System.in); stdin new Scanner(System.in) PrintWriter out = new PrintWriter(System.out); out new PrintWriter(System.out) int N = Integer.parseInt(stdin.next()); N Integer.parseInt(stdin.next()) Integer.parseInt Integer stdin.next() stdin.next stdin double v[] = new double[N]; v new double[N] N for(int i=0;i<N;i++) {
			v[i] = Integer.parseInt(stdin.next());
		} int i=0; int i=0; i 0 i<N i N i++ i++ i {
			v[i] = Integer.parseInt(stdin.next());
		} {
			v[i] = Integer.parseInt(stdin.next());
		} v[i] = Integer.parseInt(stdin.next()) v[i] v i Integer.parseInt(stdin.next()) Integer.parseInt Integer stdin.next() stdin.next stdin for(int i=0;i<N-1;i++) {
			for(int j=i+1;j<N;j++) {
				if(v[i] > v[j]) {
					double max = v[i];
					v[i] = v[j];
					v[j] = max;
				}
			}
		} int i=0; int i=0; i 0 i<N-1 i N-1 N 1 i++ i++ i {
			for(int j=i+1;j<N;j++) {
				if(v[i] > v[j]) {
					double max = v[i];
					v[i] = v[j];
					v[j] = max;
				}
			}
		} {
			for(int j=i+1;j<N;j++) {
				if(v[i] > v[j]) {
					double max = v[i];
					v[i] = v[j];
					v[j] = max;
				}
			}
		} for(int j=i+1;j<N;j++) {
				if(v[i] > v[j]) {
					double max = v[i];
					v[i] = v[j];
					v[j] = max;
				}
			} int j=i+1; int j=i+1; j i+1 i 1 j<N j N j++ j++ j {
				if(v[i] > v[j]) {
					double max = v[i];
					v[i] = v[j];
					v[j] = max;
				}
			} {
				if(v[i] > v[j]) {
					double max = v[i];
					v[i] = v[j];
					v[j] = max;
				}
			} if(v[i] > v[j]) {
					double max = v[i];
					v[i] = v[j];
					v[j] = max;
				} v[i] > v[j] v[i] v i v[j] v j {
					double max = v[i];
					v[i] = v[j];
					v[j] = max;
				} double max = v[i]; max v[i] v i v[i] = v[j] v[i] v i v[j] v j v[j] = max v[j] v j max for(int i=0;i<N-1;i++) {
			v[i+1] = (v[i]+v[i+1])/2;
		} int i=0; int i=0; i 0 i<N-1 i N-1 N 1 i++ i++ i {
			v[i+1] = (v[i]+v[i+1])/2;
		} {
			v[i+1] = (v[i]+v[i+1])/2;
		} v[i+1] = (v[i]+v[i+1])/2 v[i+1] v i+1 i 1 (v[i]+v[i+1])/2 (v[i]+v[i+1]) v[i] v i v[i+1] v i+1 i 1 2 out.println(v[N-1]) out.println out v[N-1] v N-1 N 1 out.flush() out.flush out String[] args args public class Main {
	public static void main(String[] args) {
		Scanner stdin = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		
		int N = Integer.parseInt(stdin.next());
		double v[] = new double[N];

		for(int i=0;i<N;i++) {
			v[i] = Integer.parseInt(stdin.next());
		}
		for(int i=0;i<N-1;i++) {
			for(int j=i+1;j<N;j++) {
				if(v[i] > v[j]) {
					double max = v[i];
					v[i] = v[j];
					v[j] = max;
				}
			}
		}
		
		for(int i=0;i<N-1;i++) {
			v[i+1] = (v[i]+v[i+1])/2;
		}
		
		out.println(v[N-1]);

		out.flush();
	}
	
} public class Main {
	public static void main(String[] args) {
		Scanner stdin = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		
		int N = Integer.parseInt(stdin.next());
		double v[] = new double[N];

		for(int i=0;i<N;i++) {
			v[i] = Integer.parseInt(stdin.next());
		}
		for(int i=0;i<N-1;i++) {
			for(int j=i+1;j<N;j++) {
				if(v[i] > v[j]) {
					double max = v[i];
					v[i] = v[j];
					v[j] = max;
				}
			}
		}
		
		for(int i=0;i<N-1;i++) {
			v[i+1] = (v[i]+v[i+1])/2;
		}
		
		out.println(v[N-1]);

		out.flush();
	}
	
} Main
import java.io.PrintWriter;
import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner stdin = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		
		int N = Integer.parseInt(stdin.next());
		double v[] = new double[N];

		for(int i=0;i<N;i++) {
			v[i] = Integer.parseInt(stdin.next());
		}
		for(int i=0;i<N-1;i++) {
			for(int j=i+1;j<N;j++) {
				if(v[i] > v[j]) {
					double max = v[i];
					v[i] = v[j];
					v[j] = max;
				}
			}
		}
		
		for(int i=0;i<N-1;i++) {
			v[i+1] = (v[i]+v[i+1])/2;
		}
		
		out.println(v[N-1]);

		out.flush();
	}
	
}