def flags(a: list[int]) -> int:
    size = len(a)
    if size == 0:
        return 0

    peaks = [False] * size
    for i in range(1, size):
        next_val = a[i + 1] if i + 1 < size else 0
        peaks[i] = a[i - 1] < a[i] and a[i] > next_val

    next_peak = [0] * size
    next_peak[size - 1] = -1
    for i in range(size - 2, -1, -1):
        next_peak[i] = i if peaks[i] else next_peak[i + 1]

    i = 1
    result = 0
    while i * (i - 1) <= size:
        pos = 0
        num = 0
        while pos < size and num < i:
            pos = next_peak[pos]
            if pos == -1:
                break
            num += 1
            pos += i
        i += 1
        result = max(result, num)

    return result