convert structure to matlab m-file

Convert the following structure plan into a function m-file with two inputs (M and N):

Get M and N values
if M does not equal round(M)
   Give error message that inputs must be integers
end if
if N does not equal round(N)
   Give error message that inputs must be integers
end if
while remainder of M divided by N is not zero
   Set R to the remainder of M divided by N
   Set M to be N
   Set N to be R
end while
Return final value of N as output