('CID100289319', 1),Formicacid, chloro-, 1-adamantyl ester (7CI,8CI)
('CID100087454', 1),Formicacid, chloro-, 3-(trichlorosilyl)propyl ester (8CI)
ldiff: defaultdict(<type 'list'>, {'CID100289319': [38], 'CID100087454': [47]})
f1: [38]
f2: [47]
c1: Counter({38: 1})
c2: Counter({47: 1})
The chosen was ... CID100289319