from collections import defaultdict
N,D,T = map(int,raw_input().split())
X = map(int,raw_input().split())
X.sort()
same_rem = defaultdict(list)
for x in X:
	same_rem[(x+D)%D].append(x)
ans = 0
for l in same_rem.itervalues():
	n = len(l)
	ans += n + T*2
	for i in xrange(n-1):
		if l[i] + T*D < l[i+1] - T*D:
			ans += T*2
		else:
			ans += (l[i+1] - l[i])/D - 1
print ans