#define _USE_MATH_DEFINES
#include<iostream>
#include<string>
#include<queue>
#include<cmath>
#include<map>
#include<set>
#include<list>
#include<iomanip>
#include<vector>
#include<random>
#include<functional>
#include<algorithm>
#include<stack>
#include<cstdio>
#include<bitset>
#include<unordered_map>
#include<climits>
#include<fstream>
using namespace std;
///////////////////library zone!!!!!!!!!!!!!!!!!!!!!!!!!!!!
typedef long long ll;
typedef long double ld;
#define all(a) (a).begin(),(a).end()
#define EPS (1e-5)
#define bit(n,k) ((n>>k)&1)
const ll Mod = 1000000007;
const ll mod = 998244353;
struct H {
	ll x, y;
	bool operator<(const H &b) const {
		if (x != b.x) return x < b.x;
		return y < b.y;
	}
	bool operator>(const H &b) const {
		if (x != b.x) return x > b.x;
		return y > b.y;
	}
	bool operator==(const H &b) const { return x == b.x&&y == b.y; }
	bool operator!=(const H &b) const { return (*this) != b; }
};
struct P {
	ll pos, cost;
	bool operator<(const P &b) const { return cost < b.cost; }
	bool operator>(const P &b) const { return cost > b.cost; }
};
struct B {
	ll to, cost;
};
struct E {
	ll from, to, cost;
	bool operator<(const E &b) const { return cost < b.cost; }
	bool operator>(const E &b) const { return cost > b.cost; }
};
template<typename T, typename U>
void chmin(T &a, U b) {
	if (a > b) a = b;
}
template<typename T, typename U>
void chmax(T &a, U b) {
	if (a < b) a = b;
}
template<typename T>
T max_0(T a) {
	if (a < 0) return 0;
	return a;
}
template<typename T>
T min_0(T a) {
	if (a > 0) return 0;
	return a;
}
ll read() {
	ll u;
	ll k = scanf("%lld", &u);
	return u;
}
ll gcd(ll i, ll j) {
	if (i > j) swap(i, j);
	if (i == 0) return j;
	return gcd(j%i, i);
}
ll mod_pow(ll x, ll n, ll p) {
	ll res = 1;
	while (n > 0) {
		if (n & 1) res = res * x % p;
		x = x * x % p;
		n >>= 1;
	}
	return res;
}//x^n%p
vector<string>split(string s, char c = ' ') {
	vector<string>vec;
	string h = "";
	for (int i = 0; i < s.size();) {
		int j = i;
		while (j < s.size() && s[j] != ' ') {
			h += s[j++];
		}
		if (h.size() > 0) vec.push_back(h);
		h = "";
		i = j + 1;
	}
	return vec;
}
const ll Inf = 3023372036854775807;
const int inf = 1500000000;
#define int long long
//----------------------------------------------------
int h, w, n;
H a[4000];
int dp[4000];
int fact[250000];
int inv[250000];
signed main() {
	cin >> h >> w >> n;
	for (int i = 0; i < n; i++) {
		cin >> a[i].x >> a[i].y;
	}
	sort(a, a + n);
	fact[0] = 1;
	for (int i = 1; i < 250000; i++) {
		fact[i] = fact[i - 1] * i % Mod;
	}
	for (int i = 0; i < 250000; i++) {
		inv[i] = mod_pow(fact[i], Mod - 2, Mod);
	}
	for (int i = 0; i < n; i++) {
		int res = fact[a[i].x + a[i].y - 2] * inv[a[i].x - 1] % Mod * inv[a[i].y - 1] % Mod;
		for (int j = 0; j < i; j++) {
			if (a[j].x <= a[i].x && a[j].y <= a[i].y) {
				res -= dp[j] * fact[a[i].x + a[i].y - a[j].x - a[j].y] % Mod *
					inv[a[i].x - a[j].x] % Mod * inv[a[i].y - a[j].y] % Mod;
				res %= Mod;
				res = (res + Mod) % Mod;
			}
		}
		dp[i] = res;
	}
	int sum = 0;
	for (int i = 0; i < n; i++) {
		sum += dp[i] * fact[h + w - a[i].x - a[i].y] % Mod * inv[h - a[i].x] % Mod * inv[w - a[i].y] % Mod;
		sum %= Mod;
	}
	cout << ((fact[h + w - 2] * inv[h - 1] % Mod * inv[w - 1] % Mod - sum) % Mod + Mod) % Mod << endl;
}

Measured memory_bytes: 4224