# runtest 
# Fig 38.1 
# inputs: 50, 36

import random

NUM_TRIALS = 10000

n, runs = map(int, input("n runs=? ").split())
count = 0
for i in range(NUM_TRIALS): 
  numRuns = 1
  prevFlip = random.choice(['H', 'T'])
  for j in range(n-1): 
    flip = random.choice(['H', 'T'])
    if flip != prevFlip:
      numRuns += 1
    prevFlip = flip
  if numRuns >= runs:
    count += 1
print(f"Prob of Runs >= {runs} = {(count/NUM_TRIALS):.5f}")