import java.io.*;
import java.util.StringTokenizer;

public class A {

    int sum(int n) {
        return n * (n + 1) / 2;
    }

    private void solution() throws IOException {
        int a = in.nextInt(), b = in.nextInt();
        out.println(sum(Math.abs(a - b) / 2) + sum((Math.abs(a - b) + 1) / 2));
    }

    private void run() throws IOException {
        in = new Scanner(System.in);
        out = new PrintWriter(System.out);
        solution();
        in.close();
        out.close();
    }

    private Scanner in;
    private PrintWriter out;

    public static void main(String[] args) throws IOException {
        new A().run();
    }

    private class Scanner {

        BufferedReader br;
        StringTokenizer st;

        private Scanner(InputStream is) {
            br = new BufferedReader(new InputStreamReader(is));
        }

        private String next() throws IOException {
            while (st == null || !st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
            }
            return st.nextToken();
        }

        private Integer nextInt() throws IOException {
            return Integer.parseInt(next());
        }

        private Long nextLong() throws IOException {
            return Long.parseLong(next());
        }

        private Double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }

        private void close() throws IOException {
            st = null;
            br.close();
        }
    }
}
