Make a function to count the longest consecutive numbers in list.

 

for example, if the list1 is [1, 3, 4, 5, 6]

the longest consecutive numbers are [4, 5, 6]

and the length of the numbers is 3

so the answers should be 3

 

the numbers in the list1 can increase or decrease.

 

 

The format should be like

 

def longest_run(list1)

...(statement)

...

...

return largest_length

 

if there is no consecutive number, it should return '1'