题解 | 小红的顺子

num1 = int(input())
list_all = list(map(int,input().split()))
Count =0
list_count =[]
if(num1-1==1):
    list_count.append(1)
elif (num1-1 ==2):
        if(list_all[1]==list_all[0]+1):
            list_count.append(2)
        else:
            list_count.append(1)
else:
    for i in range(0,num1-1):
        if(i< num1-2  and list_all[i+1]==list_all[i]+1):
            Count+=1
        else:
            list_count.append(Count+1)
            Count = 0
            continue
list_count.sort(reverse=True)
print(list_count[0])