n, d, t = map(int, input().split())
dic = dict()
for i in map(int, input().split()):
    j = (i % d + d) % d
    if j in dic:
        dic[j].append(i)
    else:
        dic[j] = [i]
res = 0
for k, v in dic.items():
    v.sort()
    res += len(v) + t * 2
    for i in range(len(v) - 1):
        if v[i] + t * d < v[i + 1] - t * d:
            res += t * 2
        else:
            res += (v[i + 1] - v[i]) // d - 1
print(res)