(function() {
    var a = Symbol(), b = Symbol(), c = Symbol(), d = Symbol(), e = Symbol(), f = Symbol(), g = Symbol(), h = Symbol(), i = Symbol(), j = Symbol(), k = Symbol(), l = Symbol();
    var o = {[a]:1, [b]:2, [c]:3, [d]:4, [e]:5, [f]:6, [g]:7, [h]:8, [i]:9, [j]:10, [k]:11};
    var p = {[a]:2, [b]:3, [c]:4, [d]:5, [e]:6, [f]:7, [g]:8, [h]:9, [i]:10, [j]:11, [k]:12, [l]: 13};
    var result = 0;
    for (var index = 0; index < 1000000; ++index) {
        result += o[a] ^ o[b] ^ o[c] ^ o[d] ^ o[e] ^ o[f] ^ o[g] ^ o[h] ^ o[i] ^ o[j] ^ o[k];
        var tmp = o;
        o = p;
        p = tmp;
    }
    if (result != 6500000)
        throw "Error: bad result: " + result;
})();