var f:text;i,k,p,c:longint;
begin
assign (f,'fact.in');
reset (f);
read (f,p);
close (f);
k:=0;
repeat
i:=i+1;
if i mod 5=0 then begin
                  k:=k+1;
                  c:=i div 5;
                  repeat
                  if c mod 5=0 then k:=k+1;
                  c:=c div 5;
                  until (c=0) or (k=p);
                  end;
until k=p;
assign (f,'fact.out');
rewrite (f);
write (f,i);
close (f);
end.