var n,i,j,s:longint;
phi:array[1..1000000] of longint;
f:text;
begin
assign(f,'fractii.in');reset(f);
read(f,n);
close(F);
for i:=1 to n do phi[i]:=i-1;
for i:=2 to n do begin
                j:=2*i;
                while (j<=n) do begin
                      phi[j]:=phi[j]-phi[i];
                      j:=j+i;
                      end;
                end;
s:=0;
for i:=2 to n do
s:=s+phi[i];
assign(f,'fractii.out');rewrite(f);
write(f,2*s+1);
close(f);
end.