from collections import deque

d = deque()


N, D, T = map(int, input().split())

X = deque(list(map(int, input().split())))

for _ in range(T):
    for i in range(len(X)):
        a = X.popleft()
        X.append(a - D)
        X.append(a + D)
        X.append(a)

print(len(set(X)))