('CID100000847', 2),dl-methioninesulfoxide
('CID100000847', 2),Methioninesulfoxide
('CID107408090', 1),N-alpha-tert-Butyloxycarbonyl-L-methioninesulfoxide
ldiff: defaultdict(<type 'list'>, {'CID100000847': [3, 0], 'CID107408090': [32]})
f1: [3, 0]
f2: [32]
c1: Counter({0: 1, 3: 1})
c2: Counter({32: 1})
The chosen was ... CID100000847