#include <iostream>
#include <vector>

namespace man {
constexpr inline bool chmax(int &a, const int b) noexcept {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
}

int main() {
    std::cin.tie(nullptr) -> sync_with_stdio(false);

    int n, r, max = 1, cur = 1;
    std::cin >> n;
    std::vector<int> a(n);
    for (auto &e: a) {
        std::cin >> e;
    }
    r = a[1] - a[0];
    for (int i = 0; i + 1 < n; ++i) {
        if (r == a[i + 1] - a[i]) {
            cur++;
        } else {
            man::chmax(max, cur);
            cur = 2;
            r = a[i + 1] - a[i];
        }
    }
    man::chmax(max, cur);
    std::cout << max << '\n';
}