( ( In ( either case ) ) ( , ( ( the user ) ( ( would ( have ( to ( count ( ( ( the atoms ) ( in ( the input ) ) ) ( file ( ( ( to ( determine ( the starting ) ) ) and ) ( ending ( ( position numbers ) ( of ( the ( sulfur atoms ) ) ) ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (DT either) (NN case))) (, ,) (NP (DT the) (NN user)) (VP (MD would) (VP (VB have) (S (VP (TO to) (VP (VB count) (S (NP (NP (DT the) (NNS atoms)) (PP (IN in) (NP (DT the) (NN input)))) (VP (VB file) (S (S (VP (TO to) (VP (VB determine) (NP (DT the) (NN starting))))) (CC and) (S (VP (VBG ending) (NP (NP (NN position) (NNS numbers)) (PP (IN of) (NP (DT the) (NN sulfur) (NNS atoms)))))))))))))) (. .)))
In either case, the user would have to count the atoms in the input file to determine the starting and ending position numbers of the sulfur atoms.
(ROOT (S (NP (DT The) (NN element) (NN sulfur)) (VP (VBZ has) (NP (DT the) (JJ atomic) (NN number) (CD 16))) (. .)))