import itertools

tmp = input()
X = [int(i) for i in input().strip().split()]

tmp = -1

for i in itertools.combinations(X, r=2):
  if i[0] != i[1]:
    if tmp == -1 or tmp > abs(i[0] - i[1]):
      tmp = abs(i[0] - i[1])

print(str(tmp) if tmp > -1 else 0)