var i,N: integer; s: longint;
Begin
Writeln('Nhap vao so nguyen N='); Readln(N);
s:=0;
For i:=1 to_N do s:=s+1;
Writeln('Tong cac so tu 1 den N la: ',S);
Readln
End.
uses crt;
var n,i,s:integer;
begin
clrscr;
write('nhap n='); readln(n);
s:=0;
for i:=1 to n do
s:=s+i;
writeln('ket qua la: ',s);
readln;
end.