14.Write the equation: $x_{-}\left(x_{-}\left(x_{-} \ldots-(x-1) \ldots\right)\right)=1$ (the expression contains 1999 pairs of parentheses).
14. After expanding the brackets, the signs before all $x$ standing next to each other will be different. Therefore, after expanding the brackets, the equation will take the form: $1=1$. Answer: $x$ - any number.