import sys
input = sys.stdin.readline
A, B = map(int, input().split())
if A < B: A, B = B, A
res = 0
for i in range(A + B):
  if i % 2: B -= 1
  else: A -= 1
  if i: res += 1
  if A < 0:
    res -= 1
    break
  if B < 0:
    res -= 1
    break
print(res)