function foo1(){	
document.getElementById("yang1").style.backgroundColor="#E5E5E5";	
}

function foo11(){	
document.getElementById("yang1").style.backgroundColor="#FBFBFB";	
}

function foo2(){	
document.getElementById("yang2").style.backgroundColor="#E5E5E5";	
}

function foo22(){	
document.getElementById("yang2").style.backgroundColor="#FBFBFB";	
}

function foo3(){	
document.getElementById("yang3").style.backgroundColor="#E5E5E5";	
}

function foo33(){	
document.getElementById("yang3").style.backgroundColor="#FBFBFB";	
}

function foo4(){	
document.getElementById("yang4").style.backgroundColor="#E5E5E5";	
}

function foo44(){	
document.getElementById("yang4").style.backgroundColor="#FBFBFB";	
}