def solve():
    n = int(input())
    A = [0] + list(map(int, input().split())) + [0]
    B = [False] * (n + 2)
    for i in range(2, n + 1):
        if A[i - 1] == A[i]:
            B[i - 1] = B[i] = True
    C = B[:]
    for i in range(1, n + 1):
        if not B[i] and not (B[i - 1] or B[i + 1]):
            B[i] = True
    for i in range(2, n + 1):
        if not C[i] and not (C[i - 1] or C[i + 1]):
            C[i] = True
    print(max(sum(B), sum(C)))
solve()