#include<bits/stdc++.h>
using namespace std;


int n,m,r,ans;
double tmp;
int vis[105][105];
struct ox{
	int x,y;
}a[105];
int main(){
	cin>>n>>m>>r;
	for(int i=1;i<=m;i++){
		cin>>a[i].x>>a[i].y;
	}
	for(int i=1;i<=m;i++){
		for(int j=a[i].x-r;j<=a[i].x+r;j++){
			for(int k=a[i].y-r;k<=a[i].y+r;k++){
				tmp=sqrt(pow(a[i].x-j,2)+pow(a[i].y-k,2));
				if(sqrt(tmp)<=r&&!vis[j][k]){
					vis[j][k]=1;
					ans++;
				}	
			}
		}
	}
	cout<<ans;
	return 0;
}