from collections import defaultdict

N, D, T = map(int, input().split())
X = map(int, input().split())
d = defaultdict(list)

for x in X:
    d[x % D].append(x // D)

ans = 0
for v in d.values():
    v.sort()
    ans += 2 * T + 1
    for i in range(len(v) - 1):
        ans += v[i + 1] + T - max(v[i + 1] - T - 1, v[i] + T)
print(ans)