import java.text.NumberFormat;
import java.util.Scanner;

public class Main81 {
	public static void main(String[] args) {
		Main81 p = new Main81();
	}

	public Main81() {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String[] a = new String[n];
		for(int i=0;i<n;i++)		
			a[i] = sc.next();
			
		solve(a);
	}

	private final int NUM_DIGITS = 10;
	public void solve(String[] a) {
		
		long in = 0;
		long fr = 0;
		NumberFormat nf = NumberFormat.getInstance();
		nf.setMinimumFractionDigits(NUM_DIGITS);
		for(int j=0;j<a.length;j++){
			String[] s = (a[j]+".0").split("\\.");
			long l = Long.parseLong(s[0]);
			long f = Long.parseLong(nf.format(Double.parseDouble("0."+s[1])).substring(2));
			
			in += l;
			fr = fr + f * (s[0].charAt(0) == '-' ? (-1) : 1) ;
		
		}
		in += (long)(fr/1.0e10);
		fr %= 1.0e10;
		System.out.println(String.format("%d.%010d", in ,fr));
		
	}

}