I want to ascces element in list of arrays of int64

Question

I have this data:

l = [\'10 20 10 36 30 33 400 400 -1 -1\', 
    \'100 50 50 30 60 27 70 24 -2 -2 700 700\', 
    \'300 1000 80 21 90 18 100 15 110 12 120 9 9