model ModelName
uses "mmxprs"; !gain access to the Xpress-Optimizer solver

!sample declarations section
declarations
  N = 1..8
  
  K: array(N,N) of integer
  
  x: array(N,N) of mpvar
  f: array(N,N) of mpvar
  
end-declarations

K::[0, 27, 20,  0,  0,  0, 0,  0,
	0,  0,  0, 19, 15,  0, 0,  0,
	0,  0,  0, 12,  0,  0, 9,  0,
	0,  0,  0,  0, 14, 16, 0,  0,
	0,  0,  0,  0,  0,  0, 0, 18,
	0,  0,  0,  0,  0,  0, 5, 10,
	0,  0,  0,  0,  0,  0, 0, 17]


forall(i,j in N) x(i,j) is_binary

sum(i,j in N) x(i,j) <= 8

forall(j in N | j<>1 and j<>8) do
	sum(i in N) f(i,j) = sum(k in N) f(j,k)
end-do

forall(i,j in N) do
	f(i,j) <= K(i,j)*x(i,j)
end-do


flusso := f(1,2) + f(1,3)

setparam("XPRS_VERBOSE", TRUE)

maximize(flusso)

!end-model

numarchi:= sum(i,j in N) x(i,j)

f(1,2) + f(1,3) = getobjval

minimize(numarchi)

end-model