var p,k,i:longint;
        f,g:text;
begin
        assign(f,'fact.in');
        reset(f);
        read(f,p);
        close(f);

        i:=0;
        k:=1;
        repeat
                inc(i);
                k:=k*i;
        until k mod 100=0;

        assign(g,'fact.out');
        rewrite(g);
        write(i);
        close(g);
end.