import sys
read=sys.stdin.buffer.read
readline=sys.stdin.buffer.readline
readlines=sys.stdin.buffer.readlines

n, d, t=map(int, readline().split())
x=list(map(int, readline().split()))
from collections import defaultdict
mp=defaultdict(list)
for a in x:
    q, r=divmod(a, d)
    mp[r].append(q)
ans=0
for v in mp.values():
    v.sort()
    v.append(10**10)
    l=v[0]
    xp=v[0]
    for x in v:
        if x-xp>2*t:
            ans+=xp-l+1+2*t
            l=x
        xp=x
print(ans)