Count down,...

17 07 17 = 0    
17 08 17 = 1    17 08 18 = 1
17 09 17 = 2    17 09 18 = 2
17 10 17 = 3    17 10 18 = 3
17 11 17 = 4    17 11 18 = 4
17 12 17 = 5    17 12 18 = 5
17 01 18 = 6    17 01 19 = 6
17 02 18 = 7    17 02 19 = 7
17 03 18 = 8    17 03 19 = 8
17 04 18 = 9    17 04 19 = 9
17 05 18 = 10  17 05 19 = 10
17 06 18 = 11  17 06 19 = 11
17 07 18 = 12  17 07 19 = 12

17 08 19 = 1    17 08 20 = 1
17 09 19 = 2    17 09 20 = 2
17 10 19 = 3    17 10 20 = 3
17 11 19 = 4    17 11 20 = 4
17 12 19 = 5    17 12 20 = 5
17 01 20 = 6    17 01 21 = 6
17 02 20 = 7    28 01 21 = ...7
17 03 20 = 8
17 04 20 = 9
17 05 20 = 10
17 06 20 = 11
17 07 20 = 12


#734 
#justwritesomething 
#countdown-734