#include <iostream>
#include <cmath>
using namespace std;
int a[109][109] ;
int main()
{
    int n, m, r, x, y, i, j, z, k = 0, count = 0,q=1;
    cin >> n >> m >> r;
    for (z = 0; z < m; z++)
    {
        cin >> x >> y;
        for (i = x - r; i <= x + r; i++)
        {
            if (i <= x)
            {
                k = (int)sqrt(r*r-(x-i)*(x-i));
                for (j = y - k; j <= y + k; j++)
                {
                    if (a[i][j] != 1&&i<=n&&j<=n&&i>=1&&j>=1)
                    {
                        a[i][j] = 1;
                        count++;
                    }
                }
            }
            else
            {
                k = sqrt(r*r-q*q);
                for (j = y - k; j <= y + k; j++)
                {
                    if (a[i][j] != 1&&i<=n&&j<=n&&i>=1&&j>=1)
                    {
                        a[i][j] = 1;
                        count++;
                    }
                }
                q++;
            }
        }
        q = 1;
    }
    cout << count;
    return 0;
}```