//
//
//  Codeforces: ganariya
//  AtCoder: ganariya2525
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//include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <unordered_map>
#include <climits>
#include <set>
#include <unordered_set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <queue>
#include <random>
#include <complex>
#include <regex>
#include <locale>
#include <random>
#include <type_traits>

using namespace std;

#define SHOW_VECTOR(v) {std::cerr << #v << "\t:";for(const auto& xxx : v){std::cerr << xxx << " ";}std::cerr << "\n";}
#define SHOW_MAP(v){std::cerr << #v << endl; for(const auto& xxx: v){std::cerr << xxx.first << " " << xxx.second << "\n";}}

using LL = long long;

//~~~~~~~~~~~~~~~~~~~~~_(＾～＾ ｣ ∠)_~~~~~~~~~~~~~~~~~~~~~

LL f(LL y, LL x, vector<vector<bool>> &bad, vector<vector<LL>> &dp) {
    if (y < 0 || x < 0) return 0;
    if (y == 0 && x == 0)return 1;
    if (bad[y][x]) return 0;
    if (dp[y][x] != 0)return dp[y][x];
    return dp[y][x] = f(y - 1, x, bad, dp) + f(y, x - 1, bad, dp);
}

int main() {

    while (true) {

        int n, m;
        cin >> n >> m;

        if (!(n | m)) break;

        int D;
        cin >> D;

        vector<vector<LL>> dp(n, vector<LL>(m, 0));
        vector<vector<bool>> bad(n, vector<bool>(m, false));

        for (int i = 0; i < D; i++) {
            int a, b;
            cin >> a >> b;
            a--, b--;
            bad[a][b] = true;
        }

        cout << f(n - 1, m - 1, bad, dp) << endl;

    }

    return 0;
}






































Measured memory_bytes: 3128