program dasd;
var n,i,p,nz,q:longint;
f,g:text;
x,y:boolean;
begin
assign (f,'fact.in');
reset (f);
assign (g,'fact.out');
rewrite (g);
readln (f,p);
nz:=0;
q:=1;
x:=false;
y:=false;
while nz<p do begin
        if q mod 2=0 then x:=true;
        if q mod 5=0 then y:=true;
        if (x=true) and (y=true) then begin nz:=nz+1;
                                            x:=false;
                                            y:=false;
                                            end;
                                            q:=q+1;
                                            end;
write (g,q-1);
close (f);
close (g);
end.