N,D,T = map(int,raw_input().split())
A = {}
X = map(int,raw_input().split())
for x in X:
    if x%D not in A: A[x%D] = [x/D-T, x/D+T]
    else:
        A[x%D].append(x/D-T)
        A[x%D].append(x/D+T)
ans = sum(max(a)+1-min(a) for a in A.values())
print ans