var n,p,i,k,nr,x:longint;
    f,g:text;
    s:string;
begin
assign(f,'fact.in');reset(f);
assign(g,'fact.out');rewrite(g);
readln(f,p);
k:=0;
n:=p*5;
for i:=1 to n do
    begin
    if i mod 5=0 then
       begin
       x:=i;  nr:=0;
       while x mod 5=0 do
       begin
       x :=x div 5;
       inc(nr);
       end;
       k:=k+nr;
       end;
    if k=p then
       begin
       write(g,i);
       break;
       end;
    end;
if p=0 then write(g,'1');
if p<0 then write(g,'-1');
close(f);close(G);
end.