Periodican niz

//ispitati da li je zadati niz periodican
program niz_period;

type
    niz = array[1..20] of integer;
var
 n,p,k,l:integer;
 x,y,z: niz;

 procedure UnosNiza (var n:integer;var x:niz);
 var i:integer;
 begin
    write('Broj clanova niza: ');
    readln(n);
    for i:=1 to n do
        begin
        write ('x[',i,']=');
        readln(x[i]);
        end;
 end;

 procedure StampaNiza (n:integer; x:niz);
 var i:integer;
 begin
    write('Elementi niza: ');
    for i:=1 to n-1 do  write (x[i],',');
    writeln(x[n]);
 end;

 procedure StampaNiza1 (n,p,k:integer; x:niz);
 var i:integer;
 begin
    write('Elementi niza: ');
    for i:=p to k-1 do  write (x[i],',');
    writeln(x[k]);
 end;

 function periodican(n:integer; x:niz):integer;
 //ako je x periodican rezultat je osnovni period
 //ako x nije periodican rezultat je 0
 var i,d,k,l:integer; nadjen,r:boolean;
 begin
    i:=2;
    nadjen:=false;
    periodican:=0;
    while (i<n) and not nadjen do
    begin
        if(x[1]=x[i]) then
        begin
            d:=i-1;
            r:=true;
            k:=1;
            while (k<i) and r do
            begin
                l:=k+d;
                while (l<=n) and r do
                begin
                    //writeln(k:4,l:4, x[k]:4,x[l]:4);
                    //readln;
                    r:=x[k]=x[l];
                    l:=l+d;
                end;
                k:=k+1;
            end;
        if r then begin nadjen:=true; periodican:=d; end
            else i:=i+1;
        end
        else    i:=i+1;
    end;

 end;

 begin
    UnosNiza(n,x);
    StampaNiza(n,x);
    p:=periodican(n,x);
    if p>0 then begin writeln(' periodican sa periodom ', p); stampaniza1(n,1,p,x); end
    else writeln('nije periodican');
    readln;

 end.