MOD = 10 ** 9 + 7
INF = 10 ** 10
import sys
sys.setrecursionlimit(100000000)
dy = (-1,0,1,0)
dx = (0,1,0,-1)
from collections import deque
from heapq import heapify,heappush,heappop

def main():
    n = int(input())
    a = list(map(int,input().split()))
    a = [a[0]] + a + [a[-1]]

    ans = (n + 1)//2
    cnt1 = (n + 1)//2
    cnt2 = n//2
    for i in range(1,n + 1):
        if i%2 == 0:
            if a[i - 1] == a[i] == a[i + 1]:
                cnt2 += 1
        else:
            if a[i - 1] == a[i] == a[i + 1]:
                cnt1 += 1
    ans = max(ans,cnt1,cnt2)
    print(ans)

if __name__ =='__main__':
    main()