be able to count (someone or something) on one hand
An expression used to emphasize that something is scarce, lacking, or rare. I don't know what classes to sign up for next semester. I could count the number of ones I'm actually interested in on one hand.
be able to count somebody/something on (the fingers of) one ˈhand
used to say that the total number of somebody/something is very small: She could count on the fingers of one hand the people she actually enjoyed being with.