Luogu P1789【Mc Survival】Plug the Torch Problem Solving

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This question can be purely violent:

#include<bits/stdc++.h>
//Minecraft 666
using namespace std;
int a[110][110];
int n,m,k,ans;
int main(){
    scanf("%d%d%d",&n,&m,&k);
    for(int i=1;i<=m;i++){
        int x,y;
        scanf("%d%d",&x,&y);
        a[x - 2 ][y]= 1 ;a[x- 1 ][y]= 1 ;a[x][y]= 1 ;a[x+ 1 ][y]= 1 ;a[x- 1 ][y- 1 ]= 1 ;a[x+ 1 ][y- 1 ]= 1 ;
        a[x + 2 ][y]= 1 ;a[x][y+ 2 ]= 1 ;a[x][y+ 1 ]= 1 ;a[x][y- 1 ]= 1 ;a[x] [y- 2 ]= 1 ;a[x+ 1 ][y+ 1 ]= 1 ;a[x- 1 ][y+ 1 ]= 1 ;
    }
    for(int i=1;i<=k;i++){
        int x,y;
        scanf("%d%d",&x,&y);
        a[x - 2 ][y- 2 ]= 1 ;a[x- 1 ][y- 2 ]= 1 ;a[x][y- 2 ]= 1 ;a[x+ 1 ][y- 2 ] = 1 ;a[x+ 2 ][y- 2 ]= 1 ;
        a[x - 2 ][y- 1 ]= 1 ;a[x- 1 ][y- 1 ]= 1 ;a[x][y- 1 ]= 1 ;a[x+ 1 ][y- 1 ] = 1 ;a[x+ 2 ][y- 1 ]= 1 ;
        a[x - 2 ][y]= 1 ;a[x- 1 ][y]= 1 ;a[x][y]= 1 ;a[x+ 1 ][y]= 1 ;a[x+ 2 ] [y]= 1 ;
        a[x - 2 ][y+ 1 ]= 1 ;a[x- 1 ][y+ 1 ]= 1 ;a[x][y+ 1 ]= 1 ;a[x+ 1 ][y+ 1 ]= 1 ;a [x+ 2 ][y+ 1 ]= 1 ;
        a[x - 2 ][y+ 2 ]= 1 ;a[x- 1 ][y+ 2 ]= 1 ;a[x][y+ 2 ]= 1 ;a[x+ 1 ][y+ 2 ]= 1 ;a [x+ 2 ][y+ 2 ]= 1 ;
    }
    for(int i=1;i<=n;i++)
        for(int j=1;j<=n;j++)
            if(a[i][j]==0) ans++;
    printf("%d\n",ans);
    return 0;
}