import sys
from collections import defaultdict
sys.setrecursionlimit(10**7)
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def LI2(): return list(map(int,sys.stdin.readline().rstrip()))
def S(): return sys.stdin.readline().rstrip()
def LS(): return list(sys.stdin.readline().rstrip().split())
def LS2(): return list(sys.stdin.readline().rstrip())


N,D,T = MI()
X = LI()

d = defaultdict(list)
for x in X:
    d[x % D].append(x)

ans = 0
for key in d.keys():
    A = d[key]
    A.sort()
    l = len(A)
    count = l*(2*T+1)
    for i in range(l-1):
        a,b = A[i],A[i+1]
        count -= max(0,2*T+1-(b-a)//D)
    ans += count

print(ans)