Description
In a coloring problem, no vertex can be colored using the same color as its neighbors.
Now, you are asked to check a given graph can be drawn by only 2 colors or not.
Hint: You can use graph traversal methods to draw colors
Input
Each graph starts with two numbers (0 ≤ m, n ≤ 1000), m is the numbers of all vertex in the graph, n is the numbers of all edge in the graph. The following n tuples x and y (0 ≤ x, y ≤ 1000) specifying that there will be an edge between x and y. Notice that each graph is a simple graph and connected.
Output
For each graph, output a line with “Yes” if it can be drawn by only 2 colors, else output “No”.