N, T = [int(i) for i in input().split()]

A = [int(i) for i in input().split()]



ans = 0

for i in range(N - 1):

    ans += min(A[i + 1] - A[i], T)



print((ans + T))
N, T = [int(i) for i in input().split()]

A = [int(i) for i in input().split()]



print((T + sum(min(A[i + 1] - A[i], T) for i in range(N - 1))))
N, T = [int(i) for i in input().split()]
A = [int(i) for i in input().split()]
ans = 0
for i in range(N - 1):
    ans += min(A[i + 1] - A[i], T)
print((ans + T))

N, T = [int(i) for i in input().split()]
A = [int(i) for i in input().split()]
print((T + sum(min(A[i + 1] - A[i], T) for i in range(N - 1))))

-ans = 0 -for i in range(N - 1): -    ans += min(A[i + 1] - A[i], T) -print((ans + T)) +print((T + sum(min(A[i + 1] - A[i], T) for i in range(N - 1))))