program fracti;
var phi : array [1..1000000] of longint;
    i,j,n : longint;
    S : extended;
    f,g : text;
begin
assign(f,'fractii.in');
reset(f);
assign(g,'fractii.out');
rewrite(g);
readln(f,n);

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];

S := S*2+1;

write(g,S:1:0);

close(f);
close(g);

end.