N,K = map(int,input().split())
from heapq import heappop,heappush
P = []
heappush(P,(2-2*K,2-K,K))
heappush(P,(-2*(N-K),K,2*N-K))
for i in range(N-1):
    x,l,r = heappop(P)
    while r<=0 or l>=N:
        x,l,r = heappop(P)
    mid = (l+r)//2
    heappush(P,(-(mid-l),l,mid))
    heappush(P,(-(r-mid),mid,r))
print(mid)