заранее благодарю

uses ctr;
const
n=15;
var
a,b:array [1..n] of integer;
i,j:word;
begin
randomize;
clrscr;
for i:=1 to n do a[i]:=random(100);{zapolnit'}
j:=1;
for i:=3 to n do begin b[j]:=a[i]; inc(i,2); inc(j) end;
for i:=1 to j-1 do writeln(b[i]:5);
writeln('razmer',j-1);
readkey
end.
for i:=3 to n do begin
b[j]:=a[i];
inc(i,2); inc(j)
end;
i:=3
while i<n+1 do begin
b[j]:=a[i]; inc(i,3); inc(j)
end;