#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef unsigned long long int ull;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll myRand(ll B) {
    return (ull)rng() % B;
}
inline double time() {
    return static_cast<long double>(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count()) * 1e-9;
}

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n,m; cin >> n >> m;
    int l = 0, r = n+m+1;
    auto ok = [&](int x) -> bool {
        int two = x*3, one = x;
        int nn = n, mm = m;
        int pr = min(nn, mm);
        pr = min(pr, two);
        two -= pr;
        nn -= pr, mm -= pr;
        one += two;
        return one >= (nn+mm);
    };
    while (r-l > 1) {
        int mid = (l+r)/2;
        if (ok(mid)) {
            r = mid;
        }
        else {
            l = mid;
        }
    }

    cout << r*2-1 << endl;
}