#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>
#include <numeric>
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
//constexpr long long MAX = 5100000;
constexpr long long INF = 1LL << 60;
constexpr int inf = 1000000007;
constexpr long long mod = 1000000007LL;
//constexpr long long mod = 998244353LL;
const long double PI = acos((long double)(-1));

using namespace std;
typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;

int main()
{
    /*
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    */
    int v[4]; for (int i = 0; i < 4; i++) scanf("%d", &v[i]);
    int a[3];
    int res = inf;
    for (a[0] = 1; a[0] <= 30; a[0]++) for (a[1] = a[0]; a[1] <= 30; a[1]++) for (a[2] = a[1]; a[2] <= 30; a[2]++) {
        vector<int> dp(31, inf); dp[0] = 0;
        for (int i = 0; i <= 30; i++) {
            for (int j = 0; j < 3; j++) {
                if (i + a[j] <= 30) chmin(dp[i + a[j]], dp[i] + 1);
            }
        }
        bool ok = true;
        int ans = 0;
        for (int i = 0; i < 4; i++) {
            if (dp[v[i]] == inf) { ok = false; break; }
            ans += dp[v[i]];
        }
        if (ok) chmin(res, ans);
    }
    cout << res << endl;
    return 0;
}