#include <bits/stdc++.h>
using namespace std::literals::string_literals;
using i64 = long long;
using std::cout;
using std::endl;
using std::cin;

template<typename T>
std::vector<T> make_v(size_t a){return std::vector<T>(a);}

template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts){
  return std::vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}

int main() {
	// input
	int n; scanf("%d", &n);
	assert(1 <= n and n <= (int)1e5);

	std::vector<int> a(n);
	for(int i = 0; i < n; i++) {
		scanf("%d", &a[i]);

		assert(1 <= a[i] and a[i] <= (int)1e5);
	}

	// solve
	std::vector<std::pair<int, int>> vec;
	for(int i = 0; i < n; i++) {
		if(vec.empty() or vec.back().first != a[i]) vec.push_back({a[i], 1});
		else vec.back().second++;
	}

	auto dp = make_v<int>(vec.size() + 1, 2);
	for(int i = 0; i < vec.size(); i++) {
		dp[i + 1][0] = std::max({dp[i + 1][0], dp[i][1], dp[i][0]});
		dp[i + 1][1] = std::max({dp[i + 1][1], dp[i][0] + vec[i].second});
	}
	printf("%d\n", std::max(dp.back()[0], dp.back()[1]));
	return 0;
}