for i = 1:10
    x = ceil(rand*4);

    if x == 1
        pos(2) = pos(2) + 1;
    else if x==2
        pos(2) = pos(2) - 1;
    else if x==3
        pos(1) = pos(1) -1;
    else
        pos(1) = pos(1)+1;
    end
end