program pb;
var m,n,i:longint;
r,k,l:longint;
k2:longint;
k1:real;
x:array[1..1000] of longint;
q,w:text;

begin

assign(q,'d:\problem.in');
assign(w,'d:\problem.out');
reset(q);
rewrite(w);
read(q,n,m);

for i:=1 to n do begin
x[i]:=i;
end;
k:=0;

k:=((1+n)*n) div 2;


r:=k div m;
l:=k mod m;

if r>0 then write(w,r);
if l>0 then write(w,'0');

close(q);
close(w);
end.