#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long int ll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
typedef vector<vvvl> vvvvl;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<vvb> vvvb;
typedef vector<vvvb> vvvvb;
typedef pair<ll,ll> pl;
typedef pair<ll,pl> ppl;
typedef pair<ll,ppl> pppl;
typedef pair<ll,pppl> pppppl;
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define all(a) begin(a),end(a)
#define sz(a) (int)(a).size()
#define F first
#define S second
#define bs(A,x) binary_search(all(A),x)
#define lb(A,x) (ll)(lower_bound(all(A),x)-A.begin())
#define ub(A,x) (ll)(upper_bound(all(A),x)-A.begin())
#define cou(A,x) (ll)(upper_bound(all(A),x)-lower_bound(all(A),x))
template<typename T>using min_priority_queue=priority_queue<T,vector<T>,greater<T>>;
template<class T>bool chmax(T&a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T&a,T b){if(b<a){a=b;return 1;}return 0;}
//*
using mint=modint998244353;
const ll mod=998244353;
//*/
/*
using mint=modint1000000007;
const ll mod=1000000007;
//*/
//using mint=modint;
//*
typedef vector<mint> vm;
typedef vector<vm> vvm;
typedef vector<vvm> vvvm;
typedef vector<vvvm> vvvvm;
ostream&operator<<(ostream&os,mint a){os<<a.val();return os;}
istream&operator>>(istream&is,mint&a){int x;is>>x;a=mint(x);return is;}
//*/
template<typename T1,typename T2>ostream&operator<<(ostream&os,pair<T1,T2>p){os<<p.F<<" "<<p.S;return os;}
template<typename T1,typename T2>istream&operator>>(istream&is,pair<T1,T2>&p){is>>p.F>>p.S;return is;}
template<typename T>ostream&operator<<(ostream&os,vector<T>v){rep(i,0,sz(v))os<<v[i]<<(i+1!=sz(v)?" ":"");return os;}
template<typename T>istream&operator>>(istream&is,vector<T>&v){for(T&in:v)is>>in;return is;}
int main(){
  cin.tie(0)->sync_with_stdio(0);
  cin.exceptions(cin.failbit);
  ll N,M,X,K;cin>>N>>M>>X>>K;
  vl A(N);cin>>A;
  vvl E(N);
  rep(i,0,M){
  	ll u,v;cin>>u>>v;u--;v--;
  	if(abs(A[u]-A[v])>X)continue;
  	E[u].emplace_back(v);
  	E[v].emplace_back(u);
  }
  if(K==2){
  	dsu D(N);
  	rep(i,0,N)for(auto j:E[i])D.merge(i,j);
  	auto gr=D.groups();
  	ll ans=-N;
  	for(auto g:gr)ans+=sz(g)*1ll*sz(g);
  	cout<<ans<<endl;
  	return 0;
  }
  dsu D(2*N);
  rep(i,0,N){
    ll ma=-1e18,mi=1e18;
    for(auto j:E[i]){
      if(A[i]<=A[j])D.merge(i,j+N);
      if(A[j]<=A[i])D.merge(j,i+N);
      if(A[j]<=A[i])chmax(ma,A[j]);
      if(A[j]>=A[i])chmin(mi,A[j]);
    }
    if(mi-ma<=X)D.merge(i,i+N);
  }
  ll ans=-N;
  auto gr=D.groups();
  for(auto V:gr){
    set<ll>st;
    for(auto v:V)st.emplace(v%N);
    for(auto v:V)if(v<N&&D.same(v,v+N))ans+=sz(st)*2-1;
    ll a=0;
    map<ll,ll>A;
    for(auto v:V){
      if(v<N&&!D.same(v,v+N))a++,A[D.leader(v+N)]++;
      if(v>=N&&!D.same(v,v-N))a++,A[D.leader(v-N)]++;
    }
    ans+=a*a;
    for(auto v:V)if(v<N&&!D.same(v,v+N))ans-=A[D.leader(v+N)];
  }
  cout<<ans<<endl;
  return 0;
}