Hello Cici. We can solve this by introducing another variable count into the function as shown below.
function[F_n, count] = Fibonacci(n, count)
count = 1;
if n == 2
F_n = 1;
elseif n == 1
F_n = 0;
else
[F_n_1, count_1] = Fibonacci(n-1);
[F_n_2, count_2] = Fibonacci(n-2);
F_n = F_n_1 + F_n_2;
count = count + count_1 + count_2;
end
end
Now your function returns both the 
Fibonacci number as well as the number of times the function was called.
Fibonacci number as well as the number of times the function was called.You may capture only the count in variable ans using this code snippet for the desired value of n.
[~, ans] = Fibonacci(n);
Hope this helps. :)
