Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.
If you've seen these problems, a virtual contest is not for you - solve these problems in the archive.
If you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.
Never use someone else's code, read the tutorials or communicate with other person during a virtual contest.

No tag edit access

E. Bear and Forgotten Tree 2

time limit per test

2 secondsmemory limit per test

256 megabytesinput

standard inputoutput

standard outputA tree is a connected undirected graph consisting of *n* vertices and *n* - 1 edges. Vertices are numbered 1 through *n*.

Limak is a little polar bear. He once had a tree with *n* vertices but he lost it. He still remembers something about the lost tree though.

You are given *m* pairs of vertices (*a*_{1}, *b*_{1}), (*a*_{2}, *b*_{2}), ..., (*a*_{m}, *b*_{m}). Limak remembers that for each *i* there was no edge between *a*_{i} and *b*_{i}. He also remembers that vertex 1 was incident to exactly *k* edges (its degree was equal to *k*).

Is it possible that Limak remembers everything correctly? Check whether there exists a tree satisfying the given conditions.

Input

The first line of the input contains three integers *n*, *m* and *k* () — the number of vertices in Limak's tree, the number of forbidden pairs of vertices, and the degree of vertex 1, respectively.

The *i*-th of next *m* lines contains two distinct integers *a*_{i} and *b*_{i} (1 ≤ *a*_{i}, *b*_{i} ≤ *n*, *a*_{i} ≠ *b*_{i}) — the *i*-th pair that is forbidden. It's guaranteed that each pair of vertices will appear at most once in the input.

Output

Print "possible" (without quotes) if there exists at least one tree satisfying the given conditions. Otherwise, print "impossible" (without quotes).

Examples

Input

5 4 2

1 2

2 3

4 2

4 1

Output

possible

Input

6 5 3

1 2

1 3

1 4

1 5

1 6

Output

impossible

Note

In the first sample, there are *n* = 5 vertices. The degree of vertex 1 should be *k* = 2. All conditions are satisfied for a tree with edges 1 - 5, 5 - 2, 1 - 3 and 3 - 4.

In the second sample, Limak remembers that none of the following edges existed: 1 - 2, 1 - 3, 1 - 4, 1 - 5 and 1 - 6. Hence, vertex 1 couldn't be connected to any other vertex and it implies that there is no suitable tree.

Codeforces (c) Copyright 2010-2020 Mike Mirzayanov

The only programming contests Web 2.0 platform

Server time: Jan/20/2020 08:14:52 (e1).

Desktop version, switch to mobile version.

Supported by

User lists

Name |
---|