#yuki_33

n,d,t=map(int,raw_input().split())
s=map(int,raw_input().split())
l=[]
for e in s:
 l.append(e%d)
l.sort()
res=n+t*2
for i in xrange(n-1):
 if l[i]!=l[i+1]:
  res+=t*2
 elif s[i+1]-s[i]>=(t*2+1)*d:
  res+=t*2
 else:
  res+=(s[i+1]-s[i])/d-1
print res