Имхо так:
Program solution;
Uses Crt;
Var sec, num, n1, i : Longint;
Begin
ClrScr;
Readln(sec);
num := 1;
n1 := 0;
repeat
for i := 1 to num do
begin
write(num, ' ');
n1 := n1 + 1;
if n1 >= sec then break;
end;
num := num + 1;
until n1 >= sec;
End.
