('CID100003845', 2),Quinaldicacid, 1,4-dihydro-4-oxo- (7CI,8CI)
('CID100003845', 2),Quinaldicacid, 4-hydroxy- (8CI)
('CID100224416', 1),Quinaldicacid, 4-hydroxy-5,8-dimethoxy-, ethyl ester (7CI,8CI)
ldiff: defaultdict(<type 'list'>, {'CID100224416': [49], 'CID100003845': [30, 18]})
f1: [30, 18]
f2: [49]
c1: Counter({18: 1, 30: 1})
c2: Counter({49: 1})
The chosen was ... CID100003845