Help! All the tests' results are correct ,but it don't pass

function sym(args) {

let a = Array.from(arguments); var arr = []; a.forEach(function(n) { arr.push(n.reduce(function(x,y) { if(x.indexOf(y) ==-1) { x.push(y); } return x; },[]) ); }); args = arr.reduce(function(a,b) { var c = []; var p = 0; for(var i=0;i<a.length;i++) { if((p = b.indexOf(a[i]))==-1) { c.push(a[i]); } else { b.splice(p,1);} } return c.concat(b); }); args = args.sort(function(a,b) {return a-b;}); return args; }

sym([3, 3, 3, 2, 5], [2, 1, 5, 7], [3, 4, 6, 6], [1, 2, 3]);