// O(N + M)解法

#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;
using ll = long long;
#define chmin(a,b) a = min(a,b)
#define chmax(a,b) a = max(a,b)
int main() {
   int N, M, X, K; cin >> N >> M >> X >> K;
   vector<int> A(N); rep(i,0,N) cin >> A[i];
   vector<int> plus(N, INF), minus(N, 0);
   vector<vector<int>> G(2*N);
   auto add_edge = [&G](int i, int j) -> void { G[i].push_back(j); G[j].push_back(i); };
   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) add_edge(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) add_edge(i, i + N);
   //DFSで色付ける
   vector<int> col(2*N,-1);
   auto dfs = [&](auto&&self, int v, int c) -> void {
     if (col[v] == -1) col[v] = c;
     else return;
     for (auto x: G[v]) self(self, x, c);
   };
   rep(i,0,2*N) dfs(dfs, i, i);
   ll ans = 0;
   vector<ll> cnt_col(2*N, 0);
   rep(i,0,N) if (col[i] != col[i+N]) cnt_col[col[i]] ++ ;
   rep(i,N,2*N) cnt_col[col[i]] ++ ;
   for (auto x: cnt_col) ans += x * (x - 1);
   // 複数のグループに含まれるやつについて
   vector<vector<int>> tr(2*N);
   rep(i,0,N) {
     if (col[i] < col[i+N]) tr[col[i]].push_back(col[i+N]);
     if (col[i] > col[i+N]) tr[col[i+N]].push_back(col[i]);
   }
   vector<ll> C(2*N, 0); //カウント用のやつ
   for (auto t: tr) {
     for (auto x: t) {
       ans -= C[x];
       C[x] ++ ;
     }
     for (auto x: t) C[x] -- ;
   }
   cout << ans << endl;
}