var      n,i,x:longint;
z:integer;
v:array[1..20000]of boolean;
f,g:text;
begin
for i:=2 to n do v[i]:=false;
assign(f,'ciur.in');
reset(f);
readln(f,n);
close(f);
z:=0;
for i:=2 to n do
begin
if not v[i] then begin
            inc(z);
            x:=i;
            repeat
            x:=i+x;
            v[x]:=true;
            until x>=n;end;
end;
assign(g,'ciur.out');
rewrite(g);
writeln(G,z);
close(G);
end.