11: Add solutions for section "strings".

Created by  Aaw9nJhsNmfzFih9mKyNw9mV8CgERXJkRa1kK1Kx3LQH  on August 6, 2021
WC7C4KKYKJCKURJHJR5T667JJ6WL5CL7TKLUP2VF672ZDBJTHSDQC
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