Check if a Graph is Complete
A graph is complete if all the vertices are connected to all the other vertices.
Given an undirected graph with
n vertices and m edges, you are asked to check if it’s a complete graph.
Input
The first line of the input contains two integers
n(1 ≤ v ≤ 500) and m (1 ≤ e ≤ 100 000).The following
m lines contain pairs of integers v1, v2 (1 ≤ v1, v2 ≤ v) which means that the vertex v1 is connected to the vertex v2 and vice versa.Output
The program should print
Yes if the graph is complete and No otherwise.Examples
Input | Output |
3 2
1 2
2 3
| No |
3 3
1 2
2 3
3 1 | Yes |
7 21
1 2
1 3
1 4
1 5
1 6
1 7
2 3
2 4
2 5
2 6
2 7
3 4
3 5
3 6
3 7
4 5
4 6
4 7
5 6
5 7
6 7 | Yes |
Constraints
Time limit: 2 seconds
Memory limit: 512 MB
Output limit: 1 MB