function [phi,fval] = philp(A,C)
% produce the phi that maximizes Y^{(2)} for the given (A,C)
global nstate
m = nstate;

global X0

Ain = zeros(0,m^2);
Bin = zeros(0,1);
rind = 0;
for ind1 = 1:m^2
  for ind2 = ind1+1:m^2
    x = ind2coord(ind1,[m m]);
    y = ind2coord(ind2,[m m]);
    if length(find(x~=y))==1  % Hamming dist == 1
      for s = [-1,1]
        rind = rind+1;
        Ain(rind,ind1) =  s;
        Ain(rind,ind2) = -s;
        Bin(rind,1) = 1;
      end
    end
  end
end


cc = zeros(m^2,1);
cc(1:m) = A(:,1);
cc(m+1:2*m) = -A(:,2);


[fp,fvalp] = linprog( cc,Ain,Bin);
[fn,fvaln] = linprog(-cc,Ain,Bin);
if abs(fvalp)>abs(fvaln)
  phi = fp;
  fval = fvalp;
else
  phi = fn;
  fval = fvaln;
end
return