codeforces651----A. Joysticks

//贪心，注意特判即可
#include <iostream>
using namespace std;
int main()
{
    int a,b,ans = 0;
    cin >> a >> b;
    while(a+b > 1 && (a != 1 || b != 1) && (a!=0 && b!=0))
    {
        ++ans;
        if(a > b) {a -= 2; b+=1;}
        else {a+=1; b-=2;}
    }
    cout << ans << endl;
    return 0;
}