import sys
import math

def main():
    X, K = map(int, sys.stdin.readline().split())
    if X == 1:
        result = 1.0 - 1.0 / (2 ** (K + 1))
        print("{0:.10f}".format(result))
    elif X == 2:
        if K == 1:
            print(0.5)
        else:
            # For K >= 2, approximate zeta(K) - 1 using the series sum_{n=2}^infty 1/n^K
            # Compute until the terms are smaller than 1e-15
            zeta_k = 0.0
            n = 2
            while True:
                term = 1.0 / (n ** K)
                if term < 1e-15:
                    break
                zeta_k += term
                n += 1
            print("{0:.10f}".format(zeta_k))

if __name__ == "__main__":
    main()