N = int(input())
f = input()
s_f = f.split()
s = [int(v) for v in s_f]
s.sort()

a = []
for v in range(0, N - 1):
    a.append(s[v + 1]-s[v])

a.sort()

if not a:
    print(0)
else:
    b = max(a)
    if b == 0:
        print(b)
    else:
        for v in a:
            if v > 0:
                print(v)
                break