n = int(input())
A = list(map(int, input().split()))

e = 0
for i in range(n):
    if i%2 == 0:
        e += 1
    else:
        if i != n-1:
            if A[i-1] == A[i] and A[i] == A[i+1]:
                e += 1
        else:
            if A[i-1] == A[i]:
                e += 1

o = 0
for i in range(n):
    if i%2 == 1:
        o += 1
    else:
        if i == 0:
            if A[i] == A[i+1]:
                o += 1
        elif i == n-1:
            if A[i-1] == A[i]:
                o += 1
        else:
            if A[i-1] == A[i] and A[i] == A[i+1]:
                o += 1

print(max(o, e))