import sys
input = lambda : sys.stdin.readline().rstrip()
sys.setrecursionlimit(max(1000, 10**9))
write = lambda x: sys.stdout.write(x+"\n")


d = int(input())
def sub(x):
    v = x
    while x>0:
        x = x//2
        v += x
    return v>=d
def val(x):
    v = x
    while x>0:
        x = x//2
        v += x
        if v==d:
            return v
    return v
l = 0
r = d
while l<r-1:
    m = (l+r)//2
    if sub(m):
        r = m
    else:
        l = m
# print(r, val(r))
while val(r)>d:
    r -= 1
if val(r)==d:
    print(r)
else:
    print(d)