CF1148F.Foo Fighters

You are given $n$ objects. Each object has two integer properties: $val_i$ — its price — and $mask_i$. It is guaranteed that the sum of all prices is initially non-zero.

You want to select a positive integer $s$. All objects will be modified after that. The $i$-th object will be modified using the following procedure:

• Consider $mask_i$ and $s$ in binary notation,
• Compute the bitwise AND of $s$ and $mask_i$ ($s \,\&\, mask_i$),
• If ($s \,\&\, mask_i$) contains an odd number of ones, replace the $val_i$ with $-val_i$. Otherwise do nothing with the $i$-th object.

You need to find such an integer $s$ that when the modification above is done the sum of all prices changes sign (if it was negative, it should become positive, and vice-versa; it is not allowed for it to become zero). The absolute value of the sum can be arbitrary.

你有 $n$ 个物体。每个物体有两个整数属性：$val_i$（其价格）和 $mask_i$。保证所有价格的初始总和非零。

你需要选择一个正整数 $s$。随后，所有物体都将被修改。第 $i$ 个物体将按如下步骤修改：

• 将 $mask_i$ 和 $s$ 表示为二进制形式；
• 计算 $s$ 与 $mask_i$ 的按位与（即 $s \,\&\, mask_i$）；
• 若 $s \,\&\, mask_i$ 的二进制表示中包含奇数个 $1$，则将 $val_i$ 替换为 $-val_i$；否则不对第 $i$ 个物体作任何改动。

你需要找出一个整数 $s$，使得上述修改完成后，所有价格之和变号（若原和为负，则变为正；若原和为正，则变为负；不允许总和变为零）。总和的绝对值可为任意值。

The first line contains a single integer $n$ ($1 \leq n \leq 3 \cdot 10^5$) — the number of objects.

The $i$-th of next $n$ lines contains integers $val_i$ and $mask_i$ ($-10^9 \leq val_i \leq 10^9$, $1 \le mask_i \le 2^{62} - 1$) — the price of the object and its mask.

It is guaranteed that the sum of $val_i$ is initially non-zero.

第一行包含一个整数 $n$（$1 \leq n \leq 3 \cdot 10^5$）—— 表示物体的数量。

接下来的 $n$ 行中，第 $i$ 行包含两个整数 $val_i$ 和 $mask_i$（$-10^9 \leq val_i \leq 10^9$，$1 \le mask_i \le 2^{62} - 1$）—— 分别表示该物体的价格及其掩码。

保证所有 $val_i$ 的初始总和非零。

Print an integer $s$ ($1 \le s \le 2^{62} - 1$), such that if we modify the objects as described above, the sign of the sum of $val_i$ changes its sign.

If there are multiple such $s$, print any of them. One can show that there is always at least one valid $s$.

输出一个整数 $s$（$1 \le s \le 2^{62} - 1$），使得按照上述描述修改对象后，$val_i$ 的总和的符号发生改变。

如果存在多个满足条件的 $s$，输出任意一个即可。可以证明，至少存在一个合法的 $s$。

In the first test sample all objects will change their prices except for the object with mask $151$.

So their total sum will change its sign: initially $24$, after modifications — $-28$.

In the second test sample the only object will change its price. So the total sum will change its sign.

在第一个测试样例中，所有物品的价格都会发生变化，除了掩码为 $151$ 的物品。

因此，它们的总和将改变符号：初始为 $24$，修改后为 $-28$。

在第二个测试样例中，唯一的一个物品的价格将发生变化。因此，总和将改变符号。