uses crt;
var n : integer;
i : integer;
s : integer;
begin
clrscr;
write('n = ');
readln(n);
s := 0;
for i := 1 to n do
if (i mod 3 = 0) then
s := s + i;
writeln('Summa = ',s);
readln;
end.
uses crt;
var n : integer;
i : integer;
s : integer;
begin
clrscr;
write('n = ');
readln(n);
s := 0;
for i := 1 to n do
if (i mod 3 = 0) then
s := s + i;
writeln('Summa = ',s);
readln;
end.