Round Table

Five toddlers are sitting around a round table. These toddlers, $\{1, 2, 3, 4, 5\}$, are very picky. Toddler $1$ will not sit next to toddler $2$ or $3$. Toddler $2$ will not sit next to toddler $4$. Toddler $5$ will not sit next to toddler $3$ or $4$. Toddler $5$ must sit to the left of toddler $1$. Which number toddler is sitting to the left of toddler $4$?