# import pypyjit
# pypyjit.set_param('max_unroll_recursion=-1')
from collections import *
from itertools import *
from functools import *
from heapq import *
import sys,math
input = sys.stdin.readline

N,D,T = map(int,input().split())
X = list(map(int,input().split()))
Y = defaultdict(lambda:[])
for x in X:
    q,r = divmod(x,D)
    Y[r].append(q)
    
ans = 0
for y in Y.values():
    
    if len(y)==1:
        ans += 2*T+1
        continue
    
    y.sort()
    n = len(y)
    ans += 2*T+1
    for j in range(n-1):
        
        ans += min(y[j+1]-y[j],2*T+1)
print(ans)