n,D,T=map(int,input().split())
x=list(map(int,input().split()))
x.sort()
r={}
for v in x:
  if v%D not in r:
    r[v%D]=[]
  r[v%D]+=[(v-(v%D))//D]
c=0
for i in r:
  z=[]
  for v in r[i]:
    z+=[v-T,v+T+1]
  z=sorted(set(z))
  d={v:j for j,v in enumerate(z)}
  q=[0]*len(z)
  for v in r[i]:
    q[d[v-T]]+=1
    q[d[v+T+1]]-=1
  for j in range(1,len(q)):
    q[j]+=q[j-1]
  c+=sum(z[j+1]-z[j] for j in range(len(q)) if q[j]!=0)
print(c)