Problem 2773. Find the distance between runs

Another question inspired by the answers forum:

A vector of monotonically increasing integers may contain several runs of consecutive numbers. Find out the distance between the end of runs of at least 4 consecutive numbers and the beginning of the next run of at least 4 consecutive numbers. E.g:

v = [1,2,5,6,7,8,9,20,21,22,30,31,32,33,34,35,40,41,42,43,44];

has three runs of at least 4 numbers, [5 6 7 8 9], [30,31,32,33,34,35] and [40,41,42,43,44]. So,

d = [30-9, 40-35] = [21 5]