var phi:array[1..10000] of real;
n,i,j:longint;
afis:real;
f:text;
procedure citire;
begin
assign(f,'fractii.in');reset(f);
readln(f,n);
close(f);
end;
procedure totient;
begin
for i:=1 to n do phi[i]:=i;
for i:=2 to n do
    if phi[i]=i then
                begin
                j:=i;
                while (j<=n) do
                      begin
                      phi[j]:=phi[j]/i;
                      phi[j]:=phi[j]*(i-1);
                      j:=j+i;
                      end;
                end;
end;
procedure afisare;
begin
assign(f,'fractii.out');rewrite(f);
for i:=1 to n do
afis:=afis+phi[i];
afis:=afis*2+1;
write(f,trunc(afis)-2);
close(f);
end;
begin
citire;
totient;
afisare;
end.