Find the domain of the relation S given below:

S={(16,13),(10,16),(14,8),(15,11),(13,10)}\displaystyle {S}={\left\lbrace{\left({16},-{13}\right)},{\left(-{10},-{16}\right)},{\left({14},-{8}\right)},{\left(-{15},-{11}\right)},{\left(-{13},{10}\right)}\right\rbrace}

D={}