from collections import defaultdict

n, d, t = map(int, input().split())
X = list(set(map(int, input().split())))
n = len(X)
X.sort()

R = defaultdict(list)
for i in range(n):
    q, r = divmod(X[i], d)
    R[r].append(q)
ans = 0
for L in R.values():
    m = len(L)
    ans += m
    for i in range(m - 1):
        dif = L[i + 1] - L[i]
        cnt = dif - 1
        ans += min(cnt, 2 * t)
    ans += 2 * t
print(ans)