var c,p,n,i,min:longint;
    f,g:text;
    ok:boolean;
function cifra(a:longint):longint;
var d:longint;
begin
d:=0;
repeat
if (a mod 5=0) then
   d:=d+1;
a:=a div 5;
until (a mod 5<>0) or (a=0);
cifra:=d;
end;
begin
assign(f,'fact.in');
assign(g,'fact.out');
reset(f);
rewrite(g);
readln(f,p);
i:=1;
repeat
if (i mod 5=0)then
   c:=c+cifra(i);
i:=i+1;
until (c=p) or (i=2147483647);
if (c<>p) then writeln(g,-1)
   else writeln(g,i-1);

close(f);
close(g);
end.