#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

long long DP[61];

int main()
{
	vector<int>v(4);
	cin >> v[0] >> v[1] >> v[2] >> v[3];
	sort(v.begin(), v.end());


	long long ans = INT32_MAX;
	for (int i = 1; i < 29; i++)for (int j = i + 1; j < 30; j++)for (int k = j + 1; k < 31; k++) {
		for (int l = 0; l < 61; l++)DP[l] = INT32_MAX;
		DP[0] = 0;
		for (int l = 0; l < 31; l++) {
			if (DP[l] == INT32_MAX)continue;
			DP[l + i] = min(DP[l + i], DP[l] + 1);
			DP[l + j] = min(DP[l + j], DP[l] + 1);
			DP[l + k] = min(DP[l + k], DP[l] + 1);
		}
		ans = min(ans, DP[v[0]] + DP[v[1]] + DP[v[2]] + DP[v[3]]);
	}

	cout << ans << endl;

    return 0;
}