#include<bits/stdc++.h>
using namespace std;

#define rep(i, l, r) for (int i = (int)(l); i<(int)(r); i++)
#define ll long long

const ll INF = 2e18;

int A, B, O, W;
vector<vector<int>> G;
vector<bool> seen;
int ans = 1;

void dfs(int v, int cur) {
    seen[v] = true;
    ans = max(ans, cur);
    int cnt = 0;
    for (auto to : G[v]) {
        if (!seen[to]) {
            cnt++;
            dfs(to, cur + 1);
        } 
    }
}

int main() {
    cin >> A >> B >> O >> W;
    G.resize(A+B+O+W);
    rep(i, 0, A) rep(j, 0, A) {
        G[i].push_back(j);
    }
    rep(i, 0, B) rep(j, 0, B) {
        G[A+i].push_back(A+j);
    }
    rep(i, 0, O) rep(j, 0, O) {
        G[A+B+i].push_back(A+B+j);
    }
    rep(i, 0, W) rep(j, 0, W) {
        G[A+B+O+i].push_back(A+B+O+j);
    }
    rep(i, 0, A) rep(j, A+B+O, A+B+O+W) {
        G[i].push_back(j);
    }
    rep(i, A, A+B) rep(j, A+B+O, A+B+O+W) {
        G[i].push_back(j);
    }
    rep(i, A+B+O, A+B+O+W) rep(j, 0, A+B+O) {
        G[i].push_back(j);
    }
    seen.assign(A+B+O+W, false);
    dfs(0, 1);
    seen.assign(A+B+O+W, false);
    dfs(A, 1);
    seen.assign(A+B+O+W, false);
    dfs(A+B, 1);
    seen.assign(A+B+O+W, false);
    dfs(A+B+O, 1);
    cout << ans << endl;
}