// （誤解法）考慮不足のやつ
#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i = a; i < b; i ++ )
#define all(x) x.begin(),x.end()
const int INF = 1<<30;
#define chmin(a,b) a = min(a,b)
#define chmax(a,b) a = max(a,b)
#include<atcoder/dsu>
using namespace atcoder;
int main() {
   int N, M, X, K; cin >> N >> M >> X >> K;
   vector<int> A(N); rep(i,0,N) cin >> A[i];
   dsu D(2*N);
   vector<int> plus(N, INF), minus(N, 0);
   rep(i,0,M) {
      int u, v; cin >> u >> v;
      u -- , v -- ;
      if (A[u] > A[v]) swap(u,v);
      if (A[v] - A[u] <= X) D.merge(u, v + N);
      chmin(plus[u], A[v]);
      chmax(minus[v], A[u]);
   }
   rep(i,0,N) if (K == 2 || plus[i] - minus[i] <= X) D.merge(i, i + N);
   long long ans = 0;
   auto G = D.groups();
   for (auto&&g: G) {
      for (auto&&x: g) x %= N;
      sort(all(g));
      g.erase(unique(all(g)), g.end());
   }
   vector<vector<int>> rG(N);
   rep(i,0,G.size()) for (auto x: G[i]) rG[x].push_back(i);
   rep(i,0,N) {
      if (rG[i].size() == 1) ans += (int)G[rG[i][0]].size() - 1;
      else ans += (int)G[rG[i][0]].size() + (int)G[rG[i][1]].size() - 2;
   }
   cout << ans << endl;
}