1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<algorithm>
 5 #define maxn 110
 6 using namespace std;
 7 inline int read()
 8 {
 9     int x=0;
10     bool f=1;
11     char c=getchar();
12     for(; !isdigit(c); c=getchar()) if(c=='-') f=0;
13     for(; isdigit(c); c=getchar()) x=(x<<3)+(x<<1)+c-'0';
14     if(f) return x;
15     return 0-x;
16 }
17 inline void write(int x)
18 {
19     if(x<0){putchar('-');x=-x;}
20     if(x>9)write(x/10);
21     putchar(x%10+'0');
22 }
23 struct node
24 {
25     int to,nex;
26 }edge[20*(maxn*maxn+10)];
27 int n,m,t,cnt,ans;
28 int head[20*(maxn*maxn+10)],match[20*(maxn*maxn+10)];
29 bool map[maxn*10][maxn*10],book[20*(maxn*maxn+10)];
30 int dir1[10]={0,1,-1,1,-1,2,-2,2,-2},dir2[10]={0,2,2,-2,-2,1,1,-1,-1};
31 inline void add(int x,int y)
32 {
33     cnt++;
34     edge[cnt].to=y;
35     edge[cnt].nex=head[x];
36     head[x]=cnt;
37 }
38 inline bool dfs(int u)
39 {
40     for(int i=head[u];i;i=edge[i].nex)
41     {
42         int v=edge[i].to;
43         if(!book[v])
44         {
45             book[v]=1;
46             if(!match[v]||dfs(match[v]))
47             {
48                 match[v]=u;
49                 return true;
50             }
51         }
52     }
53     return false;
54 }
55 inline int calculation(int x,int y){return m*(x-1)+y;}
56 int main()
57 {
58     n=read();m=read();t=read();
59     for(int i=1;i<=t;i++)
60     {
61         int x,y;
62         x=read();y=read();
63         map[x][y]=1;
64     }
65     for(int i=1;i<=n;i++)
66         for(int j=1;j<=m;j++)
67             if(!map[i][j])
68             {
69                 for(int k=1;k<=8;k++)
70                 {
71                     int mi=i+dir1[k],mj=j+dir2[k];
72                     if(mi>0&&mj>0&&mi<=n&&mj<=m&&!map[mi][mj]&&(mi+mj)%2==1)
73                     {
74                         add(calculation(i,j),calculation(mi,mj));
75                     }
76                 }
77             }
78     for(int i=1;i<=calculation(n,m);i++)
79     {
80         memset(book,0,sizeof(book));
81         if(dfs(i))ans++;
82     }
83     write(n*m-ans-t);
84     return 0;
85 }

请各位大佬斧正（反正我不认识斧正是什么意思）