('CID103053208', 2),(Methyl-3 nitroso-3 ureido)-1'-tri-O-acetyl-2',3',4'-beta-D-ribopyranose
('CID103053208', 2),(Methyl-3 nitroso-3 ureido)-1'-tri-O-acetyl-2',3',4'-beta-D-ribopyranose [French]
('CID116218598', 2),beta-D-Ribopyranose 1,2,3,4-Tetraacetate
('CID116218598', 2),beta-D-Ribopyranose 1,2,3,4-tetraacetate
ldiff: defaultdict(<type 'list'>, {'CID103053208': [53, 62], 'CID116218598': [21, 21]})
f1: [53, 62]
f2: [21, 21]
c1: Counter({53: 1, 62: 1})
c2: Counter({21: 2})
The chosen was  ... CID116218598