For .. do
uses crt;
var i, N, S : integer;
begin
clrscr;
readln(N);
S := 0;
for i := 1 to N do S := S + i;
write(S);
readln
end.
While .. do
uses crt;
var i, N, S : integer;
begin
clrscr;
readln(N);
S := 0; i := 1;
while i <= N do
begin
S := S + i;
i := i + 1;
end;
write(S);
readln
end.