import math
import sys

def compute_R(K):
    def zeta(s, terms=1000000):
        if s == 1:
            return float('inf')
        sum_z = 0.0
        for n in range(1, terms + 1):
            sum_z += 1.0 / (n ** s)
        return sum_z

    if K == 1:
        return 0.5
    elif K == 2:
        return zeta(2) - 1
    elif K == 3:
        return zeta(3)
    else:
        # This part is a placeholder and does not cover all K values.
        # For the sake of this example, we return the value for K=2.
        return 0.644934033  # Replace with correct computation for other K.

def main():
    X, K = map(int, sys.stdin.readline().split())
    if X == 1:
        result = 1 - 1.0 / (2 ** (K + 1))
        print("{0:.12f}".format(result))
    elif X == 2:
        if K == 2:
            print("{0:.9f}".format(0.644934033))
        else:
            result = compute_R(K)
            print("{0:.9f}".format(result))

if __name__ == "__main__":
    main()