function u = dummies(u)

[h, w] = size(u);

for i=1:w
    u(1,i) = u(2,i);
    u(h,i) = u(h-1,i);
end

for j=1:h
    u(j,1) = u(j,2);
    u(j,w) = u(j,w-1);
end

