Program fact;
 var f,g:text; np,p:longint;
 procedure initiere;
  begin
   assign (f,'fact.in'); reset (f);
   assign (g,'fact.out'); rewrite (g);
   readln (f,p);
   np:=0;
  end;
 procedure incheiere;
  begin
   close (f); close (g);
  end;
 function nc (x:longint):longint;
  var y:longint;
  begin
   y:=0;
   while (x mod 5)=0 do begin
     y:=y+1;
     x:=x div 5;
   end;
   nc:=y;
  end;
 procedure calcul;
  var x:longint;
  begin
   if p=0 then begin
     writeln (g,1);
     close (f); close (g);
     halt (0);
   end;
   x:=0;
   repeat
     x:=x+5;
     np:=np+nc (x);
   until np>=p;
   if np=p then writeln (g,x) else writeln (g,-1);
  end;
 begin
  initiere;
  calcul;
  incheiere;
 end.