Нужен пример кода метода расширения (extension methods) на языке c#

Попробуй Program PascalGuru; var s:string;    f,t:text;
function preobr(s:string):string;var i,j,p,n,sered:integer;    gl,zp,slovo:string;    m:array [1..80] of string;beginzp:='!?*,.'; gl:='аоуыэяеёюи';  p:=pos(' ',s); i:=0;        repeat        inc(i);        slovo:=copy(s,1,p-1);        m[i]:=slovo;        delete(s,1,p);        p:=pos(' ',s);        until p=0;        n:=i+1;        m[n]:=s;    for i:=1 to n do     begin    s:=m[i];       if pos(s[length(s)],zp)<>0 then p:=length(s)-1 else p:=length(s);     sered:=(p div 2)+1;    if (not odd(p)) or (p<3) then continue;     if pos(s[1],gl)=0       then continue;     if pos(s[sered],gl)=0   then continue;     if pos(s[p],gl)=0       then continue;      s[1]:=UpCase(s[1]);    s[sered]:=UpCase(s[sered]);    s[p]:=UpCase(s[p]);     m[i]:=s+'('+s[1]+','+s[sered]+','+s[p]+')';     end;         s:='';     for i:=1 to n do s:=s+m[i]+' '; preobr:=s;end;
 beginassign(f,'input.txt'); reset(f);assign(t,'output.txt'); rewrite(t); while not eof(f) do      begin      readln(f,s);      writeln(t, preobr(s) );      end;  writeln('Файл успешно записан...'); close(f);close(t);readln;end.

Var a1,a2,a3,a4,a5,a6,a7,a8,k:integer;
begin
k:=0;
read (a1,a2,a3,a4,a5,a6,a7,a8);
if (a1>0) and (a2>0) and (a3>0) and (a4>0) and (a5>0) and (a6>0) and (a7>0) and (a8>0) then
begin
if (a1 mod 3 = 0) and (a1 mod 10 = 4) then k:=k+1;
if (a2 mod 3 = 0) and (a2 mod 10 = 4) then k:=k+1;
if (a3 mod 3 = 0) and (a3 mod 10 = 4) then k:=k+1;
if (a4 mod 3 = 0) and (a4 mod 10 = 4) then k:=k+1;
if (a5 mod 3 = 0) and (a5 mod 10 = 4) then k:=k+1;
if (a6 mod 3 = 0) and (a6 mod 10 = 4) then k:=k+1;
if (a7 mod 3 = 0) and (a7 mod 10 = 4) then k:=k+1;
if (a8 mod 3 = 0) and (a8 mod 10 = 4) then k:=k+1;
writeln (k);
end else
writeln ('Неверный ввод');
end.