('CID122722080', 1),p-Aminosalicylicacid phenyl ester
('CID100171252', 1), N-Methacryloyl-5-aminosalicylicacid
ldiff: defaultdict(<type 'list'>, {'CID122722080': [15], 'CID100171252': [18]})
f1: [15]
f2: [18]
c1: Counter({15: 1})
c2: Counter({18: 1})
The chosen was ... CID122722080