('CID100094506', 2),N-Nitroso-tetrahydrooxazin-1,2 [German]
('CID100094506', 2),N-Nitroso-tetrahydrooxazin-1,2
('CID100551218', 1),N-Nitroso-2-ethyl-1,3-tetrahydrooxazine
ldiff: defaultdict(<type 'list'>, {'CID100551218': [22], 'CID100094506': [22, 13]})
f1: [22, 13]
f2: [22]
c1: Counter({13: 1, 22: 1})
c2: Counter({22: 1})
The chosen was ... CID100094506