Use the Squeeze Theorem to evaluate the following limit. If the answer is positive infinite, type "I"; if negative infinite, type "N"; and if it does not exist, type "D".

$$\displaystyle\lim_{x \to \infty} \frac{\sin{x}}{x}$$

[By using a graphing calculator, one can see that $f(x)=\displaystyle\frac{\sin{x}}{x}$ crosses its horizontal asymptote infinitely many times.]