N,D,T=map(int,raw_input().split())
X=map(int,raw_input().split())
lists=[[] for i in range(D)]
for x in X:
    lists[abs(x)%D].append(x)
ans=N
for i in range(D):
    lists[i].sort()
    if len(lists[i])>0:
        ans+=T*2
        for j in range(len(lists[i])-1):
            if X[j+1]-X[j] >= (2*T+1)*D:
                ans += T*2
            else:
                ans += (X[j+1]-X[j])/D-1
print ans