Задачи по паскалю

[Abbatik]

uses crt;
const n=300;
var s,n1,n2,i:integer;
a:array[1..n] of integer;
begin
clrscr;
a[1]:=1;
a[2]:=1;
write('Vvedite nomer s kotorogo nachinaetsa summa...');
readln(n1);
write('Vvedite kol-vo summiruemih elementov...');
readln(n2);
i:=3;
s:=0;
write(a[1]:4,a[2]:4);
repeat
a[i]:=a[i-1]+a[i-2];
write(a[i]:4);
if i>n1 then s:=s+a[i];
i:=i+1;
until i>n1+n2;
writeln;
writeln('rezultat=',s);
readkey;
end.