var a,p,x,n,d,k:longint;
    f,g:text;
    ok:boolean;
begin
assign(f,'fact.in'); reset(f);
readln(f,p); close(f);
assign(g,'fact.out'); rewrite(g);
k:=5;    ok:=true;
repeat
if p=k then begin writeln(g,'-1');
                  ok:=false;
            end
else
k:=k*5+5;
until ((k>305175780) or (ok=false));
if ok=true then
if p=0 then writeln(g,'1')
else begin
a:=0; x:=305175781; n:=1220703125;
repeat
a:=a+(p div x)*n;
n:=n div 5;
d:=(p div x)*x;
p:=p-d;
x:=(x-1)div 5;
until p=0;
writeln(g,a);
end;
close(g);
end.