from time import time from random import randint as ri N=int(input()) K=int(input()) START=time() TIME_LIMIT=4.7 Battle=0 Win=0 while time()-START<=TIME_LIMIT: Battle+=1 A=B=0 for i in range(N): A+=ri(1,6) for i in range(N): if i<K: B+=ri(4,6) else: B+=ri(1,6) if A<B: Win+=1 print(Win/Battle)