#!/usr/bin/env python3
def main():
    n = int(input())
    a = [int(input()) for _ in range(n)]

    ans = -1

    # for each peak, greedily extend as large as possible.
    # runs in O(n)

    for i in range(1, n - 1):
        # j = length of run
        j = 0
        while i - j - 1 >= 0 and i + j + 1 < n and a[i - j - 1] == a[i + j + 1] and a[i - j] > a[i - j - 1]:
            j += 1

        # ans has to be at least 3
        if j > 0:
            ans = max(ans, 2 * j + 1)

    print(ans)


if __name__ == "__main__":
    main()