import java.io.File;
import java.io.FileNotFoundException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Wynik1 {

	public static void main(String[] args) throws FileNotFoundException {
		obliczWynik("C:\\Users\\aksta\\Desktop\\Nowy folder\\dane.txt");
	}

	public static void obliczWynik(String path) throws FileNotFoundException {
		File file = new File(path);
		Scanner scan = new Scanner(file);
		List<String> wyniki = new ArrayList<String>();
		
		while (scan.hasNext()) {
			int ileElementow = Integer.parseInt(scan.next());
			double suma = 0;

			for (int i = 0; i < ileElementow; i++) {
				double element = Double.parseDouble(scan.next());
				if (i % 2 == 1) {
					suma = suma - element;
				} else {
					suma = suma + element;
				}
			}
			wyniki.add(String.valueOf(suma));
		}
		
		Path sciezkaDoPlikuWynikowego = Paths.get("wynik.bin");
		Files.write(path, wyniki, StandardOpenOption.CREATE);
	}
}