import collections
import sys
sys.setrecursionlimit(10 ** 8)
D = collections.defaultdict(int)
ans = 0
def dfs(n,m,v):
    if D[m]>v+n-1:
        return
    global ans
    D[m]=v+n-1
    n-=1
    v+=m
    if n==0 or m==0:
        ans = max(v,ans)
        return
    if m==1:
        ans = max(v+n,ans)
        return
    dfs(n,-(-m//2),v)



N,M = map(int, input().split())
for i in reversed(range(max(1,M-100),M+1)):
    dfs(N,M,0)

print(ans)