## Keep last 1000 alive, check each 100 ##
length: 2228
sum of kept alive 500500
stats      :  (2228,2048,  6): 0: 658, 1: 791, 2: 413, 3: 143, 4: 34, 5: 8, 6: 1, 
stats_alive:  (2228,2048,  6): 0: 658, 1: 791, 2: 413, 3: 143, 4: 34, 5: 8, 6: 1, 

## Keep last 20 alive, check each 100 ##
length: 458
sum of kept alive 19810
stats      :  (458,2048,  3): 0: 1636, 1: 370, 2: 38, 3: 4, 
stats_alive:  (458,2048,  3): 0: 1636, 1: 370, 2: 38, 3: 4, 

## Keep last 10 alive, check each 500 ##
length: 339
sum of kept alive 9955
stats      :  (339,2048,  3): 0: 1740, 1: 279, 2: 27, 3: 2, 
stats_alive:  (339,2048,  3): 0: 1740, 1: 279, 2: 27, 3: 2,