Problem:
Score : 600 points

Problem Statement

Snuke is standing on a two-dimensional plane. In one operation, he can move by 1 in the positive x-direction, or move by 1 in the positive y-direction.

Let us define a function f(r, c) as follows:

f(r,c) := (The number of paths from the point (0, 0) to the point (r, c) that Snuke can trace by repeating the operation above)

Given are integers r_1, r_2, c_1, and c_2.
Find the sum of f(i, j) over all pair of integers (i, j) such that r_1 ≤ i ≤ r_2 and c_1 ≤ j ≤ c_2, and compute this value modulo (10^9+7).

Constraints

1 ≤ r_1 ≤ r_2 ≤ 10^6

1 ≤ c_1 ≤ c_2 ≤ 10^6

All values in input are integers.

Input

Input is given from Standard Input in the following format:

r_1 c_1 r_2 c_2

Output

Print the sum of f(i, j) modulo (10^9+7).

Sample Input 1

1 1 2 2

Sample Output 1

14

For example, there are two paths from the point (0, 0) to the point (1, 1): (0,0) → (0,1) → (1,1) and (0,0) → (1,0) → (1,1), so f(1,1)=2.

Similarly, f(1,2)=3, f(2,1)=3, and f(2,2)=6. Thus, the sum is 14.

Sample Input 2

314 159 2653 589

Sample Output 2

602215194

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Time Limit Exceeded)


public class Main {

  private static void solve() {
    int r1 = ni();
    int c1 = ni();
    int r2 = ni();
    int c2 = ni();


    long ret = f(r2, c2) - f(r2, c1 - 1) - f(r1 - 1, c2) + f(r1 - 1, c1 - 1);
    ret %= mod;
    if (ret < 0) {
      ret += mod;
    }

    System.out.println(ret);

  }

  private static int mod = (int) 1e9 + 7;
  private static int[][] fif = enumFIF(2 * (int) 1e6, mod);

  private static long f(int r, int c) {
    if (r > c) {
      int tmp = r;
      r = c;
      c = tmp;
    }



    long ret = 0;
    for (int i = 0; i <= r; i++) {
      ret += pow(2, i, mod);
      ret %= mod;
    }

    long f = pow(2, r, mod);
    int j = 1;
    for (int i = r + 1; i <= c; i++, j++) {
      f = f * 2 - C(r + j - 1, j - 1, mod, fif) + mod;
      f %= mod;

      ret += f;
      ret %= mod;
    }

    int k = 1;
    for (int i = c + 1; i <= c + r; i++, j++, k++) {
      f = f * 2 - C(c + k - 1, k - 1, mod, fif) - C(r + j - 1, j - 1, mod, fif) + mod + mod;
      f %= mod;

      ret += f;
      ret %= mod;
    }
    return ret;
  }

  public static int[][] enumFIF(int n, int mod) {
    int[] f = new int[n + 1];
    int[] invf = new int[n + 1];
    f[0] = 1;
    for (int i = 1; i <= n; i++) {
      f[i] = (int) ((long) f[i - 1] * i % mod);
    }
    long a = f[n];
    long b = mod;
    long p = 1, q = 0;
    while (b > 0) {
      long c = a / b;
      long d;
      d = a;
      a = b;
      b = d % b;
      d = p;
      p = q;
      q = d - c * q;
    }
    invf[n] = (int) (p < 0 ? p + mod : p);
    for (int i = n - 1; i >= 0; i--) {
      invf[i] = (int) ((long) invf[i + 1] * (i + 1) % mod);
    }
    return new int[][] {f, invf};
  }

  public static long C(int n, int r, int mod, int[][] fif) {
    if (n < 0 || r < 0 || r > n)
      return 0;
    return (long) fif[0][n] * fif[1][r] % mod * fif[1][n - r] % mod;
  }


  public static long pow(long a, long n, long mod) {
    // a %= mod;
    long ret = 1;
    int x = 63 - Long.numberOfLeadingZeros(n);
    for (; x >= 0; x--) {
      ret = ret * ret % mod;
      if (n << 63 - x < 0)
        ret = ret * a % mod;
    }
    return ret;
  }


  public static void main(String[] args) {
    new Thread(null, new Runnable() {
      @Override
      public void run() {
        long start = System.currentTimeMillis();
        String debug = args.length > 0 ? args[0] : null;
        if (debug != null) {
          try {
            is = java.nio.file.Files.newInputStream(java.nio.file.Paths.get(debug));
          } catch (Exception e) {
            throw new RuntimeException(e);
          }
        }
        reader = new java.io.BufferedReader(new java.io.InputStreamReader(is), 32768);
        solve();
        out.flush();
        tr((System.currentTimeMillis() - start) + "ms");
      }
    }, "", 64000000).start();
  }

  private static java.io.InputStream is = System.in;
  private static java.io.PrintWriter out = new java.io.PrintWriter(System.out);
  private static java.util.StringTokenizer tokenizer = null;
  private static java.io.BufferedReader reader;

  public static String next() {
    while (tokenizer == null || !tokenizer.hasMoreTokens()) {
      try {
        tokenizer = new java.util.StringTokenizer(reader.readLine());
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }
    return tokenizer.nextToken();
  }

  private static double nd() {
    return Double.parseDouble(next());
  }

  private static long nl() {
    return Long.parseLong(next());
  }

  private static int[] na(int n) {
    int[] a = new int[n];
    for (int i = 0; i < n; i++)
      a[i] = ni();
    return a;
  }

  private static char[] ns() {
    return next().toCharArray();
  }

  private static long[] nal(int n) {
    long[] a = new long[n];
    for (int i = 0; i < n; i++)
      a[i] = nl();
    return a;
  }

  private static int[][] ntable(int n, int m) {
    int[][] table = new int[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        table[i][j] = ni();
      }
    }
    return table;
  }

  private static int[][] nlist(int n, int m) {
    int[][] table = new int[m][n];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        table[j][i] = ni();
      }
    }
    return table;
  }

  private static int ni() {
    return Integer.parseInt(next());
  }

  private static void tr(Object... o) {
    if (is != System.in)
      System.out.println(java.util.Arrays.deepToString(o));
  }
}