('CID102728798', 1),Galacturonicacid, methyl ester, D- (8CI)
('CID100000610', 1),Galacturonicacid, monosodium salt (8CI)
ldiff: defaultdict(<type 'list'>, {'CID100000610': [23], 'CID102728798': [24]})
f1: [24]
f2: [23]
c1: Counter({24: 1})
c2: Counter({23: 1})
The chosen was  ... CID100000610