import math

def main():
    import sys
    N, M = map(int, sys.stdin.readline().split())
    if N == 1:
        print(1)
        return
    
    if M == 1:
        print(N)
        return
    
    t0 = 0
    if M > 1:
        t0 = (M - 1).bit_length() - 1  # floor(log2(M-1))
    
    k = max(0, (N - 1) - (t0 + 1))
    sum_total = 1 + k * 1
    remaining_steps = (N - 1) - k
    x = 1
    
    for step in range(remaining_steps):
        t = remaining_steps - step - 1
        if t < 0:
            t = 0
        max_y = 2 * x
        if (max_y - 1) * (1 << t) + 1 <= M:
            x = max_y
        else:
            x = 2 * x - 1
        sum_total += x
    
    print(sum_total)

if __name__ == "__main__":
    main()