#include <algorithm>
#include <vector>

int peaks(const std::vector<int>& a)
{
    int n = static_cast<int>(a.size());
    if (n <= 2) {
        return 0;
    }

    std::vector<int> sum(n, 0);
    int last = -1;
    int dist = 0;

    for (int i = 1; i + 1 < n; ++i) {
        sum[i] = sum[i - 1];
        if (a[i] > a[i - 1] && a[i] > a[i + 1]) {
            dist = std::max(dist, i - last);
            last = i;
            ++sum[i];
        }
    }

    sum[n - 1] = sum[n - 2];
    if (sum[n - 1] == 0) {
        return 0;
    }
    dist = std::max(dist, n - last);

    int j = 0;
    for (int i = (dist >> 1) + 1; i < dist; ++i) {
        if (n % i == 0) {
            last = 0;
            for (j = i; j <= n; j += i) {
                if (sum[j - 1] <= last) {
                    break;
                }
                last = sum[j - 1];
            }
            if (j > n) {
                return n / i;
            }
        }
    }

    for (last = dist; n % last != 0;) {
        ++last;
    }

    return n / last;
}