('CID100159910', 1), Manganese(II) protoporphyrinIX
('CID100121893', 1),ProtoporphyrinIX, 5,10,15,20,22,24-hexahydro deriv. (6CI)
ldiff: defaultdict(<type 'list'>, {'CID100159910': [15], 'CID100121893': [41]})
f1: [15]
f2: [41]
c1: Counter({15: 1})
c2: Counter({41: 1})
The chosen was ... CID100159910