N = int(input())
A = [0] + list(map(int, input().split())) + [0]
ans = 0
X = 0
Y = 0
for i in range(N+1):
    if A[i] != A[i+1]:
        X += 1
        if Y >= 2:
            ans += Y+1
            Y = 0
        else:
            Y = 0
    if A[i] == A[i+1]:
        Y += 1
        if X > 2:
            ans += abs(X-2)//2
        X = 0
if X == N + 1:
    print(X//2)
else:
    print(ans)