import sys
n,m=map(int,input().split())
n1=n
m1=m
j=0
ans=0
if n1==1 or m1 ==1:
    print(0)
    sys.exit()
while n1>0 and m1>0:
    if ans%2==0 and j!=0:
        if m1>0:
            m1-=1
            ans+=1
            j+=1
        else:
            print(ans)
            sys.exit()
    elif ans%2==1 and j!=0:
        if n1>0:
            n1-=1
            ans+=1
            j+=1
    else:
        n1-=1
        m1-=1
        ans+=1
        j+=1
print(ans)