#define _USE_MATH_DEFINES
#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<int, ll> i_ll;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int u, v; ll w; };

ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;

int main() {
	vector<int> V(4);
	cin >> V[0] >> V[1] >> V[2] >> V[3];
	int mini = INT_MAX;
	for (int A = 1; A <= 30; A++)
		for (int B = A + 1; B <= 30; B++)
			for (int C = B + 1; C <= 30; C++) {
				vector<int> a(31, INT_MAX / 10);
				a[0] = 0;
				for (int i = 1; i <= 30; i++) {
					if (i >= A) a[i] = min(a[i], a[i - A] + 1);
					if (i >= B) a[i] = min(a[i], a[i - B] + 1);
					if (i >= C) a[i] = min(a[i], a[i - C] + 1);
				}
				int sum = 0;
				for (int j = 0; j < 4; j++)
					sum += a[V[j]];
				mini = min(mini, sum);
			}
	cout << mini << endl;
}