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#include <bits/stdc++.h>

using namespace std;
using ll = long long;
#define int ll
using PII = pair<int, int>;
template <typename T> using V = vector<T>;
template <typename T> using VV = vector<V<T>>;
template <typename T> using VVV = vector<VV<T>>;

#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
#define PB push_back

const ll INF = (1LL<<60);
const int MOD = 1000000007;

template <typename T> T &chmin(T &a, const T &b) { return a = min(a, b); }
template <typename T> T &chmax(T &a, const T &b) { return a = max(a, b); }
template <typename T> bool IN(T a, T b, T x) { return a<=x&&x<b; }
template<typename T> T ceil(T a, T b) { return a/b + !!(a%b); }
template<class S,class T>
ostream &operator <<(ostream& out,const pair<S,T>& a){
  out<<'('<<a.first<<','<<a.second<<')';
  return out;
}
template<class T>
ostream &operator <<(ostream& out,const vector<T>& a){
  out<<'[';
  REP(i, a.size()) {out<<a[i];if(i!=a.size()-1)out<<',';}
  out<<']';
  return out;
}

int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0};

int board[1010][1010];
signed main(void)
{
  cin.tie(0);
  ios::sync_with_stdio(false);

  int n, m, d, k;
  cin >> n >> m >> d >> k;
  V<int> x(n), y(n);
  REP(i, n) {
    cin >> x[i] >> y[i], board[y[i]][x[i]] = i;
  }

  queue<int> que;
  que.push(0);
  V<int> a(n, INF);
  a[0] = 0;

  while(que.size()) {
    int t = que.front(); que.pop();
    // 都市tから感染する都市への遷移
    for(int i=y[t]; i<=min(y[t]+d, 1000LL); ++i) {
      for(int j=x[t]; j<=min(x[t]+d, 1000LL); ++j) {
        int dist = (x[t]-j)*(x[t]-j) + (y[t]-i)*(y[t]-i);
        if(dist > d * d) break;
        if(board[i][j] != -1 && a[board[i][j]] == INF) {
          a[board[i][j]] = a[t] + 1;
          que.push(board[i][j]);
        }
      }
      for(int j=x[t]-1; j>=max(x[t]-d, 0LL); --j) {
        int dist = (x[t]-j)*(x[t]-j) + (y[t]-i)*(y[t]-i);
        if(dist > d * d) break;
        if(board[i][j] != -1 && a[board[i][j]] == INF) {
          a[board[i][j]] = a[t] + 1;
          que.push(board[i][j]);
        }
      }
    }
    for(int i=y[t]-1; i>=max(y[t]-d, 0LL); --i) {
      for(int j=x[t]; j<=min(x[t]+d, 1000LL); ++j) {
        int dist = (x[t]-j)*(x[t]-j) + (y[t]-i)*(y[t]-i);
        if(dist > d * d) break;
        if(board[i][j] != -1 && a[board[i][j]] == INF) {
          a[board[i][j]] = a[t] + 1;
          que.push(board[i][j]);
        }
      }
      for(int j=x[t]-1; j>=max(x[t]-d, 0LL); --j) {
        int dist = (x[t]-j)*(x[t]-j) + (y[t]-i)*(y[t]-i);
        if(dist > d * d) break;
        if(board[i][j] != -1 && a[board[i][j]] == INF) {
          a[board[i][j]] = a[t] + 1;
          que.push(board[i][j]);
        }
      }
    }
  }

  // k日目に流行している都市
  int ret = 0;
  REP(i, n) {
    if(a[i] <= k && k <= a[i]+m-1) {
      ret++;
    }
  }
  cout << ret << endl;

  return 0;
}