a1= new Image();
a1.src = "pic/menu/nav_a_10.png";
b1= new Image();
b1.src = "pic/menu/nav_a_11.png";
c1= new Image();
c1.src = "pic/menu/nav_a_12.png";
d1= new Image();
d1.src = "pic/menu/nav_a_13.png";
e1= new Image();
e1.src = "pic/menu/nav_a_14.png";
f1= new Image();
f1.src = "pic/menu/nav_a_15.png";