Three.

49. What are they?

Grave, Acute, and Circumflex.

50. What is the use of the Grave accent?

To mark the falling inflection.

51. What is the use of the Acute accent?

To mark the primary accent, and the rising inflection.

52. What is the use of the Circumflex?

To mark the peculiar inflection of the voice in the pronunciation of a word.

53. How many uses has the Hyphen?