FOR...DO:

uses crt;

var n,i,s: integer;

begin

clrscr;

readln(n);

for i:=1 to n do s:=s+i;

write(s);

readln;

end.

WHILE...DO:

uses crt;

var n,i,s: integer;

begin

clrscr;

readln(n);

i:=0;

while i<n do

begin

i:=i+1;

s:=s+i;

end;

write(s);

readln;

end.

`1`. For .. to .. do

uses crt;

var x, N, S : integer;

begin

clrscr;

readln(N);

S := 0;

for x := 1 to N do S := S + x;

write(S);

readln

end.

`2.` While .. do

uses crt;

var x, N, S : integer;

begin

clrscr;

readln(N);

S := 0; x := 1;

while x <= N do

    begin

        S := S + x;

        x := x + 1;

    end;

write(S);

readln

end.