Var
x: integer;
BEGIN
Repeat
Write('Ввести число от 1 до 7: ');
Readln(x);
until x in [1..7];
Case x of
1: Writeln('21 пара');
2: writeln('4 пары');
3: writeln('св');
4: writeln(св'');
5: writeln('св');
6: writeln('св');
7: writeln('нет пар');
end;
Readln
END.