import sys

sys.setrecursionlimit(10 ** 6)
from collections import *
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))

def main():
    n,d,t=MI()
    xx=LI()
    xx.sort()
    mod_d=defaultdict(list)
    for x in xx:
        mod_d[x%d].append(x//d)
    #print(mod_d)
    ans=0
    for xx in mod_d.values():
        cur=2*t+1
        for x0,x1 in zip(xx,xx[1:]):
            cur+=2*t+1-max(0,x0+2*t-x1+1)
        ans+=cur
    print(ans)

main()