number = int(input())
vilage = []
size = 0
realsize = 0
for i in range(number):
vilage.append(int(input()))
vilage.sort()
size = ((vilage[1]-vilage[0])/2) + ((vilage[2]-vilage[1])/2)
for x in range(2,number-1):
realsize = ((vilage[x]-vilage[x-1])/2) + ((vilage[x+1]-vilage[x])/2)
if realsize < size:
print(realsize)`
`