Consider the following statements:

P: There exists no simple, undirected and connected graph with 80 vertices and 77 edges.

Q: All vertices of Euler graph are of even degree.

R: Every simple, undirected, connected and acyclic graph with 50 vertices has at least two vertices of degree one.

S: There exits a bipartite graph with more than ten vertices which is 2-colorable.

What is the number of correct statements among the above statements.