Maximum number of comparisons required to merge two sorted files

1. The problem statement, all variables and given/known data
Maximum no. of comparisons required to merge two sorted files of length 'm' and 'n' is..

2. Relevant equations


3. The attempt at a solution
I think m+n-1

 

@Orodruin Please see this question


Suppose we have two list LIST-1 & LIST-2 of sorted integers of size 3, 2 respectively (say)

1. First we compare ##1^{st}## element of the both list and suppose we get minimum value from LIST-1, So we store it in the new array. Now we are having two lists of size 2, 2 (1 Comparison)
2. Now we compare ##2^{nd}## element of LIST-1 with ##1^{st}## element of LIST-2 this time element from LIST-2 becomes minimum, So we store it . Now we are having two list of size 2, 1 (1 Comparison)
3. Now we compare ##2^{nd}## element of LIST-1 with ##2^{nd}## element of LIST-2 this time element from LIST-1 becomes minimum, So we store it . Now we are having two list of size 1, 1 (1 Comparison)
4. Now we compare ##3^{rd}## element of LIST-1 with ##2^{nd}## element of LIST-2 this time element from LIST-2 becomes minimum. so we store it . Now we are having two list of size 1, 0 (1 Comparison)
5. Now we store last element left from LIST-1 to the array. Hence 3+2-1 = 4 comparisons

 

What I'm missing here

 

Your above approach also ends up with ##m+n-1## comparisons.