#include <bits/stdc++.h>

#define F first
#define S second
#define pb push_back
#define eb emplace_back
#define rsz resize
#define all(a) a.begin(), a.end()

template<class T> bool ckmax(T& a, T b){return a < b ? a = b, true : false;}
template<class T> bool ckmin(T& a, T b){return a > b ? a = b, true : false;}

using namespace std;
using ll = long long;
using ld = long double;
using vi = vector<int>;
using vll = vector<ll>;
using pii = pair<int, int>;
using vpii = vector<pair<int, int>>;
using vpll = vector<pair<ll, ll>>;

const int N = 1e6 + 5;
const ll INF = 1e18;
const ll LINF = 1e18;
const int mod = 998244353;

vector<ld> a(4), b(4);
vi p(3);

void operation(int type, int i, int j){
    if(type == 0)a[i] = a[j] = a[i] * a[j];
    if(type == 1)a[i] = a[j] = a[i] / a[j];
    if(type == 2)a[i] = a[j] = a[i] + a[j];
    if(type == 3)a[i] = a[j] = a[i] - a[j];
}

set<int> st;

void solve(){
    ld eps = 1e-8;
    for(int i = 0; i < 4; ++i){
        for(int j = 0; j < 4; ++j){
            for(int q = 0; q < 4; ++q){
                for(int k = 0; k < 4; ++k)a[k] = b[k];
                operation(i, p[0] - 1, p[0]);
                operation(j, p[1] - 1, p[1]);
                operation(q, p[2] - 1, p[2]);
               // if(p[0] == 1 && p[2] == 2 && i == 1 && q == 1)cout << a[3] << < endl;
                a[3] = a[p[2]];
                if(a[3] - int(a[3]) < eps)st.insert(a[3]);
            }
        }
    }
}

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);
    for(auto &x:b)cin >> x;
    sort(all(b));
    p = {1, 2, 3};
    do{
        sort(all(p));
        do{
             solve();
        }while(next_permutation(all(p)));
    }while(next_permutation(all(b)));
    int ans = 0;
    for(auto x:st){
       // cout << x << " ";
        if(abs(ans - 21) > abs(x - 21)) ans = x;}
    cout << ans;
    return 0;
}