1 //codeforces 559C|51nod1486 Gerald and Giant Chess(组合数学+逆元)
2
3 #include <bits/stdc++.h>
4 using namespace std;
5 #define LL long long
6 typedef pair<int,int> pii;
7 const int inf = 0x3f3f3f3f;
8 const int N =2e5+10;
9 #define clc(a,b) memset(a,b,sizeof(a))
10 const double eps = 1e-8;
11 const int MOD = 1e9+7;
12 void fre() {freopen("in.txt","r",stdin);}
13 void freout() {freopen("out.txt","w",stdout);}
14 inline int read() {int x=0,f=1;char ch=getchar();while(ch>'9'||ch<'0') {if(ch=='-') f=-1;ch=getchar();}while(ch>='0'&&ch<='9') {x=x*10+ch-'0';ch=getchar();}return x*f;}
15
16 struct Point{
17 int x,y;
18 Point(){}
19 Point(int _x,int _y):x(_x),y(_y){}
20 bool operator <(const Point &rhs) const{
21 if(x==rhs.x) return y<rhs.y;
22 return x<rhs.x;
23 }
24 }p[N];
25
26 int f[N];
27 int invv[N];
28 int inv(int x){
29 int ret=1,y=MOD-2;
30 while(y){
31 if(y&1)ret=1ll*ret*x%MOD;
32 y>>=1;x=1ll*x*x%MOD;
33 }
34 return ret;
35 }
36 int C(int n,int m){
37 if(n<m)return 0;
38 int ret=1ll*f[n]*invv[m]%MOD;
39 ret=1ll*ret*invv[n-m]%MOD;
40 return ret;
41 }
42 int lucas(int n,int m){
43 if(m == 0) return 1;
44 return 1ll*C(n % MOD, m % MOD) * lucas(n / MOD, m / MOD) % MOD;
45 }
46
47 void init(int n,int m){
48 f[0]=1;
49 invv[0]=1;
50 for(int i=1;i<=n+m+5;++i){
51 f[i]=1ll*i*f[i-1]%MOD;
52 invv[i]=inv(f[i]);
53 }
54 }
55
56 int sum[N];
57 int main(){
58 int n,m,q;
59 scanf("%d%d%d",&n,&m,&q);
60 init(n,m);
61 for(int i=1;i<=q;i++){
62 int x,y;
63 x=read(),y=read();
64 p[i]=Point(x,y);
65 }
66 p[++q]=Point(n,m);
67 sort(p+1,p+1+q);
68 for(int i=1;i<=q;i++){
69 sum[i]=lucas(p[i].x-1+p[i].y-1,p[i].x-1);
70 for(int j=1;j<i;j++){
71 sum[i]=(sum[i]-1LL*sum[j]*lucas(p[i].x-p[j].x+p[i].y-p[j].y,p[i].x-p[j].x)%MOD+MOD)%MOD;
72 }
73 }
74 printf("%d\n",sum[q]);
75 return 0;
76 }
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