Codeforces Round 161 (Div. 2)
C
Circle of Numbers
Codeforces
2000
原题
← BD →
翻译中…

One day Vasya came up to the blackboard and wrote out $*n*$ distinct integers from $1$ to $*n*$ in some order in a circle. Then he drew arcs to join the pairs of integers $(*a*, *b*)$ $(*a* ≠ *b*)$, that are either each other's immediate neighbors in the circle, or there is number $*c*$, such that $*a*$ and $*с*$ are immediate neighbors, and $*b*$ and $*c*$ are immediate neighbors. As you can easily deduce, in the end Vasya drew $2·*n*$ arcs.

翻译中…

For example, if the numbers are written in the circle in the order $1, 2, 3, 4, 5$ (in the clockwise direction), then the arcs will join pairs of integers $(1, 2)$, $(2, 3)$, $(3, 4)$, $(4, 5)$, $(5, 1)$, $(1, 3)$, $(2, 4)$, $(3, 5)$, $(4, 1)$ and $(5, 2)$.

翻译中…

Much time has passed ever since, the numbers we wiped off the blackboard long ago, but recently Vasya has found a piece of paper with $2·*n*$ written pairs of integers that were joined with the arcs on the board. Vasya asks you to find the order of numbers in the circle by these pairs.

翻译中…

Input

翻译中…

The first line of the input contains a single integer $*n*$ ($5 ≤ *n* ≤ 10^{5}$) that shows, how many numbers were written on the board. Next $2·*n*$ lines contain pairs of integers $*a*_{*i*}$, $*b*_{*i*}$ ($1 ≤ *a*_{*i*}, *b*_{*i*} ≤ *n*$, $*a*_{*i*} ≠ *b*_{*i*}$) — the numbers that were connected by the arcs.

翻译中…

It is guaranteed that no pair of integers, connected by a arc, occurs in the input more than once. The pairs of numbers and the numbers in the pairs are given in the arbitrary order.

翻译中…

Output

翻译中…

If Vasya made a mistake somewhere and there isn't any way to place numbers from $1$ to $*n*$ on the circle according to the statement, then print a single number "-1" (without the quotes). Otherwise, print any suitable sequence of $*n*$ distinct integers from $1$ to $*n*$.

翻译中…

If there are multiple solutions, you are allowed to print any of them. Specifically, it doesn't matter which number you write first to describe the sequence of the order. It also doesn't matter whether you write out the numbers in the clockwise or counter-clockwise direction.

翻译中…

样例

Input #1
5
1 2
2 3
3 4
4 5
5 1
1 3
2 4
3 5
4 1
5 2
Output #1
1 2 3 4 5
InputCopy OutputCopy
Input #2
6
5 6
4 3
5 3
2 4
6 1
3 1
6 2
2 5
1 4
3 6
1 2
4 5
Output #2
1 2 4 5 3 6
InputCopy OutputCopy
题目信息
题号
263C
时间限制
2 s
内存限制
256 MB
标签
暴力
DFS 及类似
模拟

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。