function A(q: string): string;
var g: char;
    i: integer;
begin
     writeln('- Введите символ' + #13 + '> ');
     readln(g);
     i := 1;
     while (i <= length(q)) do
     begin
         if (q[i] = g) then
         begin
              insert(g + g, q, i + 1);
              i := i + 2;
         end;
         inc(i);
     end;
     result := q;
end;

function B(q: string): string;
var g: string;
    i: integer;
begin
     for i := 1 to length(q) do
     begin
         if (q[i] in ['a'..'z', 'A'..'Z', 'А'..'я', 'А'..'Я']) then g := g + q[i] + q[i];
         if (q[i] in ['0'..'9']) then g := g + q[i];
     end;
     result := g;
end;

function C(q: string): string;
var g: string;
    i: integer;
begin
     for i := 1 to length(q) do
         g := g + q[i] + q[i];
     result := g;
end;

function D(q: string): string;
var g: string;
    i: integer;
begin
     i := 1;
     while (i <= length(q)) do
     begin
          g := g + q[i];
          if (q[i] = ' ') then
               g := g + ' ';
          inc(i);
     end;
     result := g;
end;

var str: string;
    w: char;
begin
     write('Введите строку' + #13 + '> ');
     readln(str);
     write('Введите букву задания' + #13 + '> ');
     readln(w);
     case (w) of
          'А':
              writeln(A(str));
          'Б':
              writeln(B(str));
          'В':
              writeln(C(str));
          'Г':
              writeln(D(str));
     end;
end.