#include<iostream>
int a[101][101],sum;
int dis(int x0,int y0,int x1,int y1)
{
    return (x1-x0)*(x1-x0)+(y1-y0)*(y1-y0);
}
int main()
{
    int n,m,r;
    std::cin>>n>>m>>r;
    for(int i=1;i<=m;i+=1)
    {
        int x,y;
        std::cin>>x>>y;
        for(int j=1;j<=n;j+=1)for(int k=1;k<=n;k+=1)if(r*r>=dis(x,y,j,k))a[j][k]=1;
    }
    for(int i=1;i<=n;i+=1)for(int j=1;j<=n;j+=1)if(a[i][j])sum+=1;
    std::cout<<sum;
}