import sys
readline = sys.stdin.readline
N = int(readline())
A = list(map(int, readline().split()))
dpz = [0]*N
dpm = [0]*N
dpz[0] = 1

for i in range(1, N):
    ap = A[i-1]
    an = A[i]
    if ap == an:
        dpz[i] = 1 + max(dpz[i-1], dpm[i-1])
        dpm[i] = max(dpz[i-1], dpm[i-1])
    else:
        dpz[i] = 1 + dpm[i-1]
        dpm[i] = max(dpz[i-1], dpm[i-1])

print(max(dpm[N-1], dpz[N-1]))