while True:
    try:
        n=int(input())
        l=list(map(int,input().split()))
        a=[]
        for i in range(0,n-2):
            a.append(l[i+2]-l[i])
        j=a.index(min(a))
        del l[j+1]
        b=[]
        for i in range(len(l)):
            b.append(l[i]-l[i-1])
        print(max(b))
    except:
        break