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

public class Main {
	
	static int[] v;
	static int[] w;
	static long[][] dp;
	
	public static void main(String[] args) throws IOException {
		FastScanner sc = new FastScanner(System.in);
		
		while(true){
			int a = sc.nextInt();
			int b = sc.nextInt();
			if(a == 0 && b == 0) break;
			int n = sc.nextInt();
			boolean[][] cannot = new boolean[a][b];
			for(int i = 0; i < n; i++){
				int aa = sc.nextInt()-1;
				int bb = sc.nextInt()-1;
				cannot[aa][bb] = true;
			}
			
			int[][] dp = new int[a][b];
			dp[0][0] = 1;
			
			for(int i = 0; i < a; i++){
				for(int j = 0; j < b; j++){
					if(i+1 < a && !cannot[i+1][j])
						dp[i+1][j] += dp[i][j];
					if(j+1 < b && !cannot[i][j+1])
						dp[i][j+1] += dp[i][j];
				}
			}
			
			System.out.println(dp[a-1][b-1]);
		}
		
	}//end main
	
	public static long solve(int i, int j){
		if(i == 0 || j == 0) return 0;
		if(dp[i][j] > 0) return dp[i][j];
		
		if(j - w[i] < 0){
			dp[i][j] = solve(i-1, j);
			return dp[i][j];
		}else{
			dp[i][j] = Math.max(solve(i-1, j), solve(i-1, j-w[i]) + v[i]);
			return dp[i][j];
		}
	}
}//end Main

class FastScanner {
    private InputStream in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    public FastScanner(InputStream in) {
		this.in = in;
	}
    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        }else{
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }
    private int readByte() {
    	if (hasNextByte()) return buffer[ptr++];
    	else return -1;
    }
    private static boolean isPrintableChar(int c){
    	return 33 <= c && c <= 126;
    }
    public boolean hasNext() {
    	while(hasNextByte() && !isPrintableChar(buffer[ptr]))
    		ptr++; return hasNextByte();
    }
    public String next() {
        if (!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public long nextLong() {
        if (!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while(true){
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
        return (int) nl;
    }
    public double nextDouble() {
    	return Double.parseDouble(next());
    }
}



Measured memory_bytes: 23892