var f,g:text;
    n,p,nr,x,y:longint;
    ok:boolean;
procedure verificare;
begin
x:=5;
y:=0;
while x<=nr do begin
  y:=y+nr div x;
  x:=sqr(x);
end;
if y=p then ok:=true else nr:=nr-5;
end;
begin
assign(f,'fact.in'); reset(f);
assign(g,'fact.out'); rewrite(g);
read(f,p);
nr:=p*10;
ok:=false;
while not ok do verificare;
write(g,nr);
close(g);
end.