If a problem "X" is in "C" and hard for "C", then "X" is said to be "complete" for "C". This means that "X" is the hardest problem in "C". (Since many problems could be equally hard, one might say that "X" is one of the hardest problems in "C".) Thus the class of NP-complete problems contains the most difficult problems in NP, in the sense that they are the ones most likely not to be in P. Because the problem P = NP is not solved, being able to reduce a known NP-complete problem, Π2, to another problem, Π1, would indicate that there is no known polynomial-time solution for Π1. This is because a polynomial-time solution to Π1 would yield a polynomial-time solution to Π2. Similarly, because all NP problems can be reduced to the set, finding an NP-complete problem that can be solved in polynomial time would mean that P = NP.