program factorial;

const fin = 'fact.in';
     fout = 'fact.out';

var p,n,answer: longint;

procedure load;
 var f: text;
begin
 assign(f, fin); reset(f);
  readln(f,p);
 close(f);
end;

function sum5(l: longint): byte;
 var s: byte;
begin
 s:=0;
 while l>0 do
    begin
         s:=s+ (l mod 5);
         l:=l div 5;
    end;
 sum5:=s;
end;

procedure getn;
 var m: longint;
begin
 for m:=4*p to 4*p + 52 do
     begin
          if 4*p = m-sum5(m) then
             begin
                  answer:=m;
                  exit;
             end;
     end;
 answer:=-1;
end;

procedure save;
 var f: text;
begin
 assign(f, fout); rewrite(f);
 write(f, answer);
 close(f);
end;

begin
 load;
 if p=0 then answer:=1
        else getn;
 save;
end.