35pts，测试点五彩斑斓，求条

n=int(input())
s=[]
cha=[]
d=0
for _ in range(n):
    a=int(input())
    s.append(a)
for i in range(len(s)):
    for j in range(i+1,len(s)):
        cha.append(abs(s[i]-s[j]))
for k in range(1,max(cha)):
    for l in cha:
        if l%k==0:
            break
    else:
        print(k)
        break