#include <bits/stdc++.h>
using namespace std;
//#include <atcoder/all>
//using namespace atcoder;
using ll = long long;
using vll = vector<ll>;
using vvll = vector<vll>;
#define all(A) A.begin(),A.end()
#define rep(i, n) for (ll i = 0; i < (ll) (n); i++)
using pqr = priority_queue<pair<ll, ll>, vector<pair<ll, ll>>, greater<pair<ll, ll>>>;

template<class T>
bool chmax(T& p, T q, bool C = 1) {
    if (C == 0 && p == q) {
        return 1;
    }
    if (p < q) {
        p = q;
        return 1;
    }
    else {
        return 0;
    }
}

template<class T>
bool chmin(T& p, T q, bool C = 1) {
    if (C == 0 && p == q) {
        return 1;
    }
    if (p > q) {
        p = q;
        return 1;
    }
    else {
        return 0;
    }
}

ll gcd(ll(a), ll(b)) {
    if (b == 0)return a;
    ll c = a;
    while (a % b != 0) {
        c = a % b;
        a = b;
        b = c;
    }
    return b;
}
ll sqrtz(ll N) {
    ll L = 0;
    ll R = sqrt(N) + 10000;
    while (abs(R - L) > 1) {
        ll mid = (R + L) / 2;
        if (mid * mid <= N)L = mid;
        else R = mid;
    }
    return L;

}
vector<ll> fact, factinv, inv;
const ll mod = 998244353;
void prenCkModp(ll n) {
    fact.resize(n + 5);
    factinv.resize(n + 5);
    inv.resize(n + 5);
    fact[0] = fact[1] = 1;
    factinv[0] = factinv[1] = 1;
    inv[1] = 1;
    for (ll i = 2; i < n + 5; i++) {
        fact[i] = (fact[i - 1] * i) % mod;
        inv[i] = mod - (inv[mod % i] * (mod / i)) % mod;
        factinv[i] = (factinv[i - 1] * inv[i]) % mod;
    }

}

ll nCk(ll n, ll k) {
    if (n < k) return 0;
    return fact[n] * (factinv[k] * factinv[n - k] % mod) % mod;
}

ll inva(ll N) {
    ll a = N, b = mod, c = 1, d = 0;
    while (b > 0) {
        ll t = a / b;
        a -= t * b;
        swap(a, b);
        c -= t * d;
        swap(c, d);

    }
    c %= mod;
    if (c < 0)c += mod;
    return c;

}
vll A, B;
ll N;
unordered_map<ll, ll> MF, MB;

ll p = 0;
ll t = 1;
void dfs(ll n) {
    if (n == -1) {
        MF[p] += t;
        MF[p] %= mod;
    }
    else {
        rep(i, 11) {
            p += A[n] * i;
            t *= nCk(10, i);
            t %= mod;
            dfs(n - 1);
            p -= A[n] * i;
            t *= inva(nCk(10, i));
            t %= mod;
        }
    }
}

void dfsp(ll n) {
    if (n == N) {
        MB[p] += t;
        MB[p] %= mod;
    }
    else {
        rep(i, 11) {
            p += A[n] * i;
            t *= nCk(10, i);
            t %= mod;
            dfsp(n + 1);
            p -= A[n] * i;
            t *= inva(nCk(10, i));
            t %= mod;
        }
    }
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    ll X,Y;
    cin>>X>>Y;
    rep(i,12){
        if(X==i||Y==i)continue;
        vll D={X,Y,i};
        sort(all(D));
        if(D[2]-D[1]==4&&D[1]-D[0]==4){
            cout<<i<<endl;
            return 0;
        }
    }
    
}