30pt

#include<bits/stdc++.h>
using namespace std;
int r,c,n;
int main()
{
	cin>>r>>c>>n;
	int ans = r*c-n*13;
	cout<<ans<<"\n"; 
	return 0;
}

60pt

#include<bits/stdc++.h>
using namespace std;
int r,c,n;
bool flag[1005][1005];
int main()
{
	cin>>r>>c>>n;
	for(int i=1;i<=r;i++)
		for(int j=1;j<=c;j++)
			flag[i][j] = false;
	for(int i=1;i<=n;i++)
	{
		int x,y;
		cin>>x>>y;
		flag[x-2][y] = true;
		flag[x-1][y] = true;
		flag[x][y] = true;
		flag[x+1][y] = true;
		flag[x+2][y] = true;
		flag[x][y-2] = true;
		flag[x][y-1] = true;
		flag[x][y+1] = true;
		flag[x][y+2] = true;
		flag[x-1][y-1] = true;
		flag[x-1][y+1] = true;
		flag[x+1][y-1] = true;
		flag[x+1][y+1] = true;
	}
	int ans=0;
	for(int i=1;i<=r;i++)
		for(int j=1;j<=c;j++)
		{
			if(flag[i][j]==false)
				ans++;
		} 
	cout<<ans<<"\n"; 
	return 0;
}

100pt

#include<bits/stdc++.h>
using namespace std;
int r,c,n;
bool flag[1005][1005];
int main()
{
	cin>>r>>c>>n;
	for(int i=1;i<=r;i++)
		for(int j=1;j<=c;j++)
			flag[i][j] = false;
	for(int i=1;i<=n;i++)
	{
		int x,y;
		cin>>x>>y;
		if(x-2>=1)
			flag[x-2][y] = true;
		flag[x-1][y] = true;
		flag[x][y] = true;
		flag[x+1][y] = true;
		flag[x+2][y] = true;
		if(y-2>=1)
			flag[x][y-2] = true;
		flag[x][y-1] = true;
		flag[x][y+1] = true;
		flag[x][y+2] = true;
		flag[x-1][y-1] = true;
		flag[x-1][y+1] = true;
		flag[x+1][y-1] = true;
		flag[x+1][y+1] = true;
	}
	int ans=0;
	for(int i=1;i<=r;i++)
		for(int j=1;j<=c;j++)
		{
			if(flag[i][j]==false)
				ans++;
		} 
	cout<<ans<<"\n"; 
	return 0;
}

#include <bits/stdc++.h>
using namespace std;
int r, c;
int g[1005][1005];
int n, x, y;
void f(int x, int y)
{
    if (x < 1 || x > r || y < 1 || y > c)
        return;
    g[x][y] = 1;
}
void fire(int x, int y)
{
    f(x - 2, y);
    f(x - 1, y - 1), f(x - 1, y), f(x - 1, y + 1);
    f(x, y - 2), f(x, y - 1), f(x, y), f(x, y + 1), f(x, y + 2);
    f(x + 1, y - 1), f(x + 1, y), f(x + 1, y + 1);
    f(x + 2, y);
}
int main()
{
    cin >> r >> c;
    for (int i = 1; i <= r; i++)
        for (int j = 1; j <= c; j++)
            g[i][j] = 0;
    cin >> n;
    for (int i = 1; i <= n; i++)
    {
        cin >> x >> y;
        fire(x, y);
    }
    int ans = 0;
    for (int i = 1; i <= r; i++)
        for (int j = 1; j <= c; j++)
            if (g[i][j] == 0)
                ans++;
    cout << ans << "\n";
    return 0;
}