There are $N$ people on a number line.
Person $i$ $(1\le i\le N)$ is initially at coordinate $S_i$, and wants to eventually move to coordinate $T_i$. It is guaranteed that $S_1,S_2,\ldots,S_N,T_1,T_2,\ldots,T_N$ are all distinct.
You fix one permutation $P=(P_1,P_2,\ldots,P_N)$ of $(1,2,\ldots,N)$ and perform $N$ operations in order. In the $i$\-th operation $(1\le i\le N)$, you move person $P_i$ from coordinate $S_{P_i}$ to coordinate $T_{P_i}$ along the shortest path on the number line. However, if there is another person on the movement path, a fight occurs.
Determine if there exists a $P$ such that no fight occurs, and if it exists, find one.
## Constraints
* $1\le N\le 2\times 10^5$
* $1\le S_i, T_i \le 10^9$
* $S_1,S_2,\ldots,S_N,T_1,T_2,\ldots,T_N$ are all distinct.
* All input values are integers.
## Input
The input is given from Standard Input in the following format:
$N$
$S_1$ $T_1$
$S_2$ $T_2$
$\vdots$
$S_N$ $T_N$
[samples]