type ta=array [1..1000000] of 0..1;  
      ta2=array [1..1000000] of int64;        
 var f:text;        
     d,suma,n,cop,p:int64;        
     i,j:longint;        
     a:ta;        
     t:ta2;        
 begin       
 assign(f,'fractii.in');reset(f);        
 read(f,n);        
 close(f);        
 for i:=2 to n do       
     if a[i]=0 then       
        for j:=2 to (n div i) do       
            a[i*j]:=1;        
 suma:=1;        
 for i:=1 to n do       
     begin       
     if a[i]=0 then t[i]:=i-1       
               else       
   
     
     suma:=suma+t[i];        
     end;        
 assign(f,'fractii.out');rewrite(f);        
        
 close(f);        
 end.