function (rand) {
                function stage1() {
                        var a = Array.apply(null, new Array(Math.floor(Math.random() * 20) + 10)).map(function () {return Math.random() * 0x10000;});
                        var b = rand(a.length);

                        if (!Array.isArray(b)) {
                                print("You're a cheater!");
                                return false;
                        }

                        if (b.length < a.length) {
                                print("hmm.. too short..");
                                for (var i = 0, n = a.length - b.length; i < n; i++) {
                                        delete b[b.length];
                                        b[b.length] = [Math.random() * 0x10000];
                                }
                        } else if (b.length > a.length) {
                                print("hmm.. too long..");
                                for (var i = 0, n = b.length - a.length; i < n; i++)
                                        Array.prototype.pop.apply(b);
                        }

                        for (var i = 0, n = b.length; i < n; i++) {
                                if (a[i] != b[i]) {
                                        print("ddang~~");
                                        return false;
                                }
                        }

                        return true;
                }

                function stage2() {
                        var a = Array.apply(null, new Array((myRand() % 20) + 10)).map(function () {return myRand() % 0x10000;});
                        var b = rand(a.length);

                        if (!Array.isArray(b)) {
                                print("You're a cheater!");
                                return false;
                        }

                        if (b.length < a.length) {
                                print("hmm.. too short..");
                                for (var i = 0, n = a.length - b.length; i < n; i++) {
                                        delete b[b.length];
                                        b[b.length] = [Math.random() * 0x10000];
                                }
                        } else if (b.length > a.length) {
                                print("hmm.. too long..");
                                for (var i = 0, n = b.length - a.length; i < n; i++)
                                        Array.prototype.pop.apply(b);
                        }

                        for (var i = 0, n = b.length; i < n; i++) {
                                if (a[i] != b[i]) {
                                        print("ddang~~");
                                        return false;
                                }
                        }

                        return true;
                }

                print("stage1");

                if (!stage1())
                        return;

                print("stage2");

                if (!stage2())
                        return;

                print("awesome!");
                return flag;
        }