rand('state',0);
n=10;m=20;
edges=[[1 1 1 2 2 2 3 3 4 4 5 5 6 6 7 7 8 7 8 9]'...
    [2 3 4 6 3 4 5 6 6 7 8 7 7 8 8 9 9 10 10 10]'];
A=zeros(n,m);
for j=1:size(edges,1)
    A(edges(j,1),j)=-1;A(edges(j,2),j)=1;
end
a=2*rand(m,1);
x_max = 1+rand(m,1);B=m/2;

% code to plot the graph (if you have biograph)
%G=sparse(edges(:,1),edges(:,2),1,n,n);
%view(biograph(G));