Counting values between values in array

I have a variable, call it var, containing thousands of rows of numbers, like so:

123
124
125
128 % some values skipped
129
130
132
% etc

I want to give two values, then count the number of values in the data between (and including) these two values.

For example, if I gave A = 123, B = 129, then I would want it to count in the data and return an output of 5.

I also want to be able to give values that are skipped (though they wouldn't be counted). For example, if I gave A=126 and B=128, I would want an output of 1. Or if I gave A = 128 and B = 131, then I would want an output of 3.

How could this be done? I would like to to be done quickly, because the values reach into the hundreds of thousands.

Answer 1

[KALYAN ACHARJYA]

A=123;
B=129;
result=sum(find(var==A | var==B))