#include <bits/stdc++.h>

using namespace std;

#define all(x) begin(x), end(x)

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using vi = vector<int>;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);

    int n;
    cin >> n;
    vi a(n);

    for (auto& x : a) {
        cin >> x;
    }

    // Size of the i-th mochi is A[i]
    vector<int> b;
    int last_val = -1;
    int last_count = 0;
    for (int i = 0; i < n; ++i) {
        if (a[i] == last_val) {
            ++last_count;
        } else {
            if (last_count > 0) {
                b.push_back(last_count);
            }

            last_val = a[i];
            last_count = 1;
        }
    }

    if (last_count > 0) {
        b.push_back(last_count);
    }

    vi dp(b.size() + 1, 0);
    dp[1] = b[0];
    for (int i = 1; i < b.size(); ++i) {
        dp[i + 1] = max(b[i] + dp[i - 1], dp[i]);
    }

    cout << *max_element(all(dp)) << '\n';
    
    return 0;
}