('CID100277084', 1),Cyclohexanepropionicacid, 3-carboxy- (6CI,8CI)
('CID100098393', 1),Cyclohexanepropionicacid, 2-oxo- (6CI,7CI)
ldiff: defaultdict(<type 'list'>, {'CID100098393': [18], 'CID100277084': [22]})
f1: [22]
f2: [18]
c1: Counter({22: 1})
c2: Counter({18: 1})
The chosen was  ... CID100098393