// 想定誤解法というか、愚直にやった場合について
#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);
   dsu E(N);
   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); E.merge(u,v); }
      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 = E.groups();
   for (auto g: G) {
      for (int i = 0; i < g.size(); i ++ ) {
         for (int j = i + 1; j < g.size(); j ++ ) {
            int a0 = D.leader(g[i]);
            int a1 = D.leader(g[i]+N);
            int b0 = D.leader(g[j]);
            int b1 = D.leader(g[j]+N);
            if (a0 == b0 || a0 == b1 || a1 == b0 || a1 == b1) {
               ans ++ ;
            }
         }
      }
   }
   cout << ans * 2 << endl;
}