n,d,t=map(int, raw_input().split())
dic={}
for i in map(int,raw_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():
 res+=len(v)+t*2
 for i in xrange(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