N = int(input())
vs = sorted(list(map(int, input().split())))

max_ = vs[-1]
diffs = []
pre_v = vs[0]
for v in vs[1:]:
    diffs.append(v-pre_v)
    pre_v = v


while len(diffs) != 1:
    index, min_ = min(enumerate(diffs), key = lambda x:x[1])

    if index >= 1 :
        diffs[index-1] += min_/2
    if index <= len(diffs)-2:
        diffs[index+1] += min_/2

    del diffs[index]

print(max_-diffs[0]/2)