#include <cstdint>
#include <iostream>
#include <vector>

int main() {
    int32_t m;
    std::cin >> m;

    std::vector<int32_t> freq(202, 0);
    for (int32_t i = 0; i < m; ++i) {
        int32_t x;
        std::cin >> x;
        ++freq[x];
    }

    int32_t ans = 1;
    for (int32_t i = 1; i < freq.size(); ++i) {
        if (!freq[i]) continue;

        int32_t cf = 1 + (i % 2);
        int32_t cur = (i + 1 + cf) / 2;
        while (cf < freq[i]) {
            ++cur;
            cf += 2;
        }

        ans = std::max(ans, cur);
    }

    std::cout << ans << '\n';

    return 0;
}