I need help with this task

Question

The task is done in C++.
The task sounds like this:
In a matrix ( any size ) from each column take the biggest and smallest number and subtract the smallest from the highest.
Thanks in advance 😀

https://code.sololearn.com/c3HwfVcuSYXW

Answer 1

Well the finding of the biggest and smallest number
I know how to do it but just can't figure out which number I need to compare

Answer 2

Just some instructions;
a= matrix
i=row
j=column
n=number of columns/rows
m=the smallest number
v=the biggest number
r=the subtraction between biggest and smallest
b=array to put the subtractions