var n:Number = 4;
var str:String = "";

for(var i = 1;i<n*2;i++){
    var t:Number = i;
    if(i>n){
        t = (n*2)-i;
    }
    for(j = 0;j<Math.abs(t);j++){
        str += "*";
    }
    str += "\n";
}
trace(str);