('CID102736987', 1),p-Anisicacid, 3,5-difluoro- (8CI)
('CID100017823', 1),p-Anisicacid, 3-amino- (7CI,8CI)
ldiff: defaultdict(<type 'list'>, {'CID102736987': [21], 'CID100017823': [20]})
f1: [21]
f2: [20]
c1: Counter({21: 1})
c2: Counter({20: 1})
The chosen was  ... CID100017823