Problem: There is a grid with H horizontal rows and W vertical columns. Let (i, j) denote the square at the i-th row from the top and the j-th column from the left.

In the grid, N Squares (r_1, c_1), (r_2, c_2), \ldots, (r_N, c_N) are wall squares, and the others are all empty squares. It is guaranteed that Squares (1, 1) and (H, W) are empty squares.

Taro will start from Square (1, 1) and reach (H, W) by repeatedly moving right or down to an adjacent empty square.

Find the number of Taro's paths from Square (1, 1) to (H, W), modulo 10^9 + 7.

Constraints

* All values in input are integers.
* 2 \leq H, W \leq 10^5
* 1 \leq N \leq 3000
* 1 \leq r_i \leq H
* 1 \leq c_i \leq W
* Squares (r_i, c_i) are all distinct.
* Squares (1, 1) and (H, W) are empty squares.

Input

Input is given from Standard Input in the following format:


H W N
r_1 c_1
r_2 c_2
:
r_N c_N


Output

Print the number of Taro's paths from Square (1, 1) to (H, W), modulo 10^9 + 7.

Examples

Input

3 4 2
2 2
1 4


Output

3


Input

5 2 2
2 1
4 2


Output

0


Input

5 5 4
3 1
3 5
1 3
5 3


Output

24


Input

100000 100000 1
50000 50000


Output

123445622

Solution (in JAVA):

Solution:
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Arrays;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.io.Closeable;
import java.io.Writer;
import java.io.OutputStreamWriter;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) throws Exception {
        Thread thread = new Thread(null, new TaskAdapter(), "", 1 << 27);
        thread.start();
        thread.join();
    }

    static class TaskAdapter implements Runnable {
        @Override
        public void run() {
            InputStream inputStream = System.in;
            OutputStream outputStream = System.out;
            FastInput in = new FastInput(inputStream);
            FastOutput out = new FastOutput(outputStream);
            TaskY solver = new TaskY();
            solver.solve(1, in, out);
            out.close();
        }
    }

    static class TaskY {
        public void solve(int testNumber, FastInput in, FastOutput out) {
            Modular mod = new Modular(1e9 + 7);
            Composite comp = new Composite(200000, mod);
            int h = in.readInt();
            int w = in.readInt();
            int n = in.readInt();
            Block[] blocks = new Block[n];
            for (int i = 0; i < n; i++) {
                blocks[i] = new Block();
                blocks[i].r = in.readInt() - 1;
                blocks[i].c = in.readInt() - 1;
            }
            Arrays.sort(blocks, (a, b) -> Integer.compare(a.r + a.c, b.r + b.c));
            for (int i = 0; i < n; i++) {
                blocks[i].dp[1] = comp.composite(blocks[i].r + blocks[i].c,
                        blocks[i].r);
                for (int j = 0; j < i; j++) {
                    if (blocks[j].r > blocks[i].r ||
                            blocks[j].c > blocks[i].c) {
                        continue;
                    }
                    for (int t = 0; t < 2; t++) {
                        blocks[i].dp[t] = mod.plus(blocks[i].dp[t],
                                mod.mul(blocks[j].dp[1 - t],
                                        comp.composite(blocks[i].r - blocks[j].r
                                                        + blocks[i].c - blocks[j].c,
                                                blocks[i].r - blocks[j].r)));
                    }
                }
            }

            int sum = comp.composite(h + w - 2, h - 1);
            for (Block b : blocks) {
                int remain = comp.composite(h + w - 2 - b.r - b.c, h - 1 - b.r);
                sum = mod.plus(sum, mod.mul(remain, b.dp[0]));
                sum = mod.subtract(sum, mod.mul(remain, b.dp[1]));
            }

            out.println(sum);
        }

    }

    static class Composite {
        final Factorial factorial;
        final Modular modular;

        public Composite(Factorial factorial) {
            this.factorial = factorial;
            this.modular = factorial.getModular();
        }

        public Composite(int limit, Modular modular) {
            this(new Factorial(limit, modular));
        }

        public int composite(int m, int n) {
            if (n > m) {
                return 0;
            }
            return modular.mul(modular.mul(factorial.fact(m), factorial.invFact(n)), factorial.invFact(m - n));
        }

    }

    static class Modular {
        int m;

        public int getMod() {
            return m;
        }

        public Modular(int m) {
            this.m = m;
        }

        public Modular(long m) {
            this.m = (int) m;
            if (this.m != m) {
                throw new IllegalArgumentException();
            }
        }

        public Modular(double m) {
            this.m = (int) m;
            if (this.m != m) {
                throw new IllegalArgumentException();
            }
        }

        public int valueOf(int x) {
            x %= m;
            if (x < 0) {
                x += m;
            }
            return x;
        }

        public int valueOf(long x) {
            x %= m;
            if (x < 0) {
                x += m;
            }
            return (int) x;
        }

        public int mul(int x, int y) {
            return valueOf((long) x * y);
        }

        public int plus(int x, int y) {
            return valueOf(x + y);
        }

        public int subtract(int x, int y) {
            return valueOf(x - y);
        }

        public String toString() {
            return "mod " + m;
        }

    }

    static class InverseNumber {
        int[] inv;

        public InverseNumber(int[] inv, int limit, Modular modular) {
            this.inv = inv;
            inv[1] = 1;
            int p = modular.getMod();
            for (int i = 2; i <= limit; i++) {
                int k = p / i;
                int r = p % i;
                inv[i] = modular.mul(-k, inv[r]);
            }
        }

        public InverseNumber(int limit, Modular modular) {
            this(new int[limit + 1], limit, modular);
        }

    }

    static class FastOutput implements AutoCloseable, Closeable {
        private StringBuilder cache = new StringBuilder(10 << 20);
        private final Writer os;

        public FastOutput(Writer os) {
            this.os = os;
        }

        public FastOutput(OutputStream os) {
            this(new OutputStreamWriter(os));
        }

        public FastOutput println(int c) {
            cache.append(c).append('\n');
            return this;
        }

        public FastOutput flush() {
            try {
                os.append(cache);
                os.flush();
                cache.setLength(0);
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }
            return this;
        }

        public void close() {
            flush();
            try {
                os.close();
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }
        }

        public String toString() {
            return cache.toString();
        }

    }

    static class FastInput {
        private final InputStream is;
        private byte[] buf = new byte[1 << 13];
        private int bufLen;
        private int bufOffset;
        private int next;

        public FastInput(InputStream is) {
            this.is = is;
        }

        private int read() {
            while (bufLen == bufOffset) {
                bufOffset = 0;
                try {
                    bufLen = is.read(buf);
                } catch (IOException e) {
                    bufLen = -1;
                }
                if (bufLen == -1) {
                    return -1;
                }
            }
            return buf[bufOffset++];
        }

        public void skipBlank() {
            while (next >= 0 && next <= 32) {
                next = read();
            }
        }

        public int readInt() {
            int sign = 1;

            skipBlank();
            if (next == '+' || next == '-') {
                sign = next == '+' ? 1 : -1;
                next = read();
            }

            int val = 0;
            if (sign == 1) {
                while (next >= '0' && next <= '9') {
                    val = val * 10 + next - '0';
                    next = read();
                }
            } else {
                while (next >= '0' && next <= '9') {
                    val = val * 10 - next + '0';
                    next = read();
                }
            }

            return val;
        }

    }

    static class Block {
        int r;
        int c;
        int[] dp = new int[2];

    }

    static class Factorial {
        int[] fact;
        int[] inv;
        Modular modular;

        public Modular getModular() {
            return modular;
        }

        public Factorial(int[] fact, int[] inv, InverseNumber in, int limit, Modular modular) {
            this.modular = modular;
            this.fact = fact;
            this.inv = inv;
            fact[0] = inv[0] = 1;
            for (int i = 1; i <= limit; i++) {
                fact[i] = modular.mul(fact[i - 1], i);
                inv[i] = modular.mul(inv[i - 1], in.inv[i]);
            }
        }

        public Factorial(int limit, Modular modular) {
            this(new int[limit + 1], new int[limit + 1], new InverseNumber(limit, modular), limit, modular);
        }

        public int fact(int n) {
            return fact[n];
        }

        public int invFact(int n) {
            return inv[n];
        }

    }
}