Step 1: Divide the number into separate digits:
54339 => 5 4 3 3 9
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
5 to 4 => 1
4 to 3 => 1
3 to 3 => 0
3 to 9 => 6
9 to 5 => 4
Step 3: Convert distances to codes (0=E[qual],
1 & 9 = C[onsecutive], 2-8 = N[one]):
1 => C
1 => C
0 => E
6 => N
4 => N
Step 4: Combine the filters to a string:
C C E N N = CCENN