# include <bits/stdc++.h>
using namespace std;
# define x first
# define y second
# define fi cin
# define fo cout
# define ll long long
const int mod = 2000003;
ll dp[6005];
pair < int , int > s[6005];
int f[1 << 21];
int pw(int a,int b)
{
    int ans = 1;
    while (b)
    {
        if (b&1) ans = (1ll * ans * a) % mod;
        a = (1ll * a * a) % mod;
        b /= 2;
    }
    return ans;
}
int C(int a,int b)
{
    return (((1ll * f[b] * pw(f[a],mod-2) % mod) * pw(f[b - a],mod-2))) % mod;
}
int main(void)
{
    ifstream fi("padure2.in");
    ofstream fo("padure2.out");
    int h,w,n;
    fi>>h>>w>>n;
    for (int i = 1;i <= n;++i) fi>>s[i].x>>s[i].y;
    sort(s+1,s+1+n);
    s[++n] = make_pair(h,w);
    f[0] = 1;
    const int N = 2e6;
    for (int i = 1;i <= N;++i)
    {
        f[i] = (1ll * i * f[i-1]) % mod;
    }
    for (int i = 1;i <= n;++i)
    {
        dp[i] = C(s[i].x - 1,s[i].x + s[i].y - 2);
        for (int j = i - 1;j;--j)
            if (s[j].x <= s[i].x && s[j].y <= s[i].y)
                {
                    ll p = C(s[i].x - s[j].x,s[i].x + s[i].y - s[j].x - s[j].y);
                    p *= dp[j];
                    p %= mod;
                    dp[i] -= p;
                    if (dp[i] < 0) dp[i] += mod;
                }
        dp[i] %= mod;
    }
    return fo << dp[n] << '\n',0;
}