In each question, the first and the last sentences of the passage are numbered S1 and S6 respectively. The rest of the passage is split into four parts. These four sentences are jumbled. Read the sentences and identify their correct and logical order.

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S1: The study of speech disorders due to brain injury suggests that patients can think without having adequate control over their language.
P : But they succeed in playing games of chess.
Q : Some patients, for example fail to find the names of objects presented to them.
R : They can even use the concepts needed for chess playing, though they are unable to express many of the concepts in ordinary language.
S : They even find it difficult to interpret long written notices.
S6: How they manage to do this we do not know.
The Proper sequence should be: