from collections import *

N, D, T = map(int, input().split())
DD = defaultdict(list)
X = list(map(int, input().split()))
for x in X:
    r = x % D
    DD[r].append((x - r)//D)

ans = 0
for k, lst in DD.items():
    pre = -10**18
    lst.sort()
    for v in lst:
        ans += min(2 * T + 1, v - pre)
        pre = v
print(ans)