n,*a=map(int,open(0).read().split())
if n==1:exit(print(1))
r=c=2;d=a[1]-a[0]
for i in range(1,len(a)-1):c,d,r=(c+1 if a[i+1]-a[i]==d else 2),(a[i+1]-a[i]if c==2 else d),max(r,c)
print(r)