từ 1 đến N
program TinhTong;
var
N, Tong, Buoc: Integer;
begin
write('N: ');
readln(N);
Tong := 0;
Buoc := 1;
while Buoc <= N do
begin
Tong := Tong + Buoc;
Buoc := Buoc + 1;
end;
writeln('Tong cac buoc tu 1 den ', N, ' la: ', Tong);
readln;
end.