('CID100308121', 1),(4-Methoxybenzoyl)pyruvicacid methyl ester
('CID100083084', 1),Pyruvicacid, isobutyl ester (6CI,7CI)
ldiff: defaultdict(<type 'list'>, {'CID100308121': [31], 'CID100083084': [26]})
f1: [31]
f2: [26]
c1: Counter({31: 1})
c2: Counter({26: 1})
The chosen was  ... CID100083084