Program P1;
var n, k, i, r : integer;
begin
writeln ('Vvedite N:');
readln (n);
writeln ('Vvedite K:');
readln (k);
r:=0;
for i:=1 to n-1 do
if i mod k=0 then r:=r+i;
writeln (r);
readln;
end.