Ответ: var a1,a2,a3,a4:real;begin readln(a1,a2,a3,a4);if (a1<>a2) and (a1<>a3) then writeln(a1);if (a2<>a1) and (a2<>a3) then writeln(a2);if (a3<>a1) and (a3<>a2) then writeln(a3);if (a4<>a3) and (a4<>a2) then writeln(a4);end.