def mirror_ins(itr, ins, index_based: bool = True):
    leng = len(itr)
    if leng % 2:
        # The length of iterable is odd
        middle = leng // 2
        if ins == middle:
            return middle if index_based else itr[middle]
        else:
            distance = abs(ins - middle)
            if ins > middle:
                mirror = ins - (distance * 2)
                return mirror if index_based else itr[mirror]
            else:
                mirror = ins + distance * 2
                return mirror if index_based else itr[mirror]
    else:
        # The length of iterable is even
        middles = ((leng // 2) - 1, leng // 2)
        if ins in middles:
            if ins == middles[0]:
                return middles[1] if index_based else itr[middles[1]]
            else:
                return middles[0] if index_based else itr[middles[0]]
            
        else:
            distance = abs(ins - middles[1])
            if ins > middles[1]:
                mirror = ins - (distance * 2 - 1)
                return mirror if index_based else itr[mirror]
            else:
                mirror = ins + (distance * 2 - 1)
                return mirror if index_based else itr[mirror]


def ask_input():
    n = int(input())
    pillars = list(map(int, input().split()))
    return pillars


if __name__ == "__main__":
    pillars = ask_input()
    min_shot = 0
    for i in range(len(pillars) // 2):
        mirror = mirror_ins(pillars, i, False)
        if pillars[i] == mirror:
            continue
        min_shot += abs(pillars[i] - mirror)
    else:
        del i, mirror
        print(min_shot)