from bisect import bisect_right

N,K,L,U = map(int,input().split())
A = list(map(int,input().split()))
A.sort()
now_li = 0
now_ui = bisect_right(A,U-L+A[0]) - 1
now_l = A[0]

if now_ui == N-1:
    print(0)
else:
    while now_ui < N-1:
        if A[now_ui+1] - (now_l + U - L) < A[now_li+1] - now_l:
            now_l = A[now_ui+1] - U + L
            now_ui += 1
        else:
            now_l = A[now_li]
            now_li += 1
        if N - 1 - now_ui <= now_li:
            break
    now_u = now_l + U - L
    ans = 0
    for a in A:
        ans += max(now_l - a + K - 1, 0)//K
        ans += max(a - now_u + K - 1, 0)//K
    print(ans)