program factorial;
var f : text;
    p,s,i,n : longint;


begin
    assign(f,'fact.in'); reset(f);
    read(f,p);
    close(f);

    s := 1; i := 1; n := 0;

    while n < p do begin
        if i mod 5 = 0 then begin
            s := (s*i) mod 100000;
            while s mod 10 = 0 do begin
                n := n+1;
                s := s div 10;
                end;
            end
        else s := (s*i) mod 100000;
        i := i+1;
        end;

    assign(f,'fact.out'); rewrite(f);
    if p = 0 then write(f,1)
    else if n = p then write(f,i-1)
    else write(f,-1);
    close(f);
end.