from collections import defaultdict


class UnionFind():
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * n

    def find(self, x):
        if self.parents[x] < 0:
            return x
        else:
            self.parents[x] = self.find(self.parents[x])
            return self.parents[x]

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)

        if x == y:
            return

        if self.parents[x] > self.parents[y]:
            x, y = y, x

        self.parents[x] += self.parents[y]
        self.parents[y] = x

    def size(self, x):
        return -self.parents[self.find(x)]

    def same(self, x, y):
        return self.find(x) == self.find(y)

    def members(self, x):
        root = self.find(x)
        return [i for i in range(self.n) if self.find(i) == root]

    def roots(self):
        return [i for i, x in enumerate(self.parents) if x < 0]

    def group_count(self):
        return len(self.roots())

    def all_group_members(self):
        group_members = defaultdict(list)
        for member in range(self.n):
            group_members[self.find(member)].append(member)
        return group_members

    def __str__(self):
        return '\n'.join(f'{r}: {m}' for r, m in self.all_group_members().items())

n, m, x, k = list(map(int, input().split()))
A = list(map(int, input().split()))
node = [[] for _ in range(n)]
if k == 2:
    uf = UnionFind(n)
    for _ in range(m):
        u, v = list(map(lambda x: int(x)-1, input().split()))
        if abs(A[u]-A[v]) <= x:
            uf.union(u, v)
    ans = 0
    D = uf.all_group_members()
    for d in D:
        l = len(D[d])
        ans += l * (l-1)
    print(ans)
else:
    from random import randrange as R
    uf = UnionFind(2*n)
    for _ in range(m):
        u, v = list(map(lambda x: int(x)-1, input().split()))
        if abs(A[u]-A[v]) <= x:
            node[u].append(v)
            node[v].append(u)
            if A[u] < A[v]:
                uf.union(2*u+1, 2*v)
            else:
                uf.union(2*u+1, 2*v)
    for now in range(n):
        if not node[now]: continue
        node[now].sort(key = lambda x: A[x])
        f = 1
        for i in range(len(node[now])-1):
            if A[node[now][i+1]] - A[node[now][i]] > x:
                f = 0
        if f:
            uf.union(2*now, 2*now+1)
    D = uf.all_group_members()
    #print(D)
    ans = 0
    #L = [R(0, 998244353) for _ in range(2*n)]
    for d in D:
        B = D[d]
        C = set()
        for b in B:
            C.add(b//2)
        ans += len(C) * (len(C)-1)
    E = {}
    for now in range(n):
        if not uf.same(2*now, 2*now+1):
            u0, u1 = uf.find(2*now), uf.find(2*now+1)
            if u0 > u1:
                u0, u1 = u1, u0
            if not (u0, u1) in E:
                E[(u0, u1)] = 1
            else:
                E[(u0, u1)] += 1
    for e in E:
        a = E[e]
        ans -= a * (a-1)
    print(ans)