#include <iostream>
#include <string>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <vector>
#include <cmath>
#include <cstdlib>
#include <queue>
#include <stack>
#include <iomanip>

using namespace std;

#define REP(i, n) for(ll i = 0;i < n;i++)
#define REPR(i, n) for(ll i = n;i >= 0;i--)
#define FOR(i, m, n) for(ll i = m;i < n;i++)
#define FORR(i, m, n) for(ll i = m;i >= n;i--)
#define REPO(i, n) for(ll i = 1;i <= n;i++)
#define ll long long
#define INF (ll)1 << 60
#define MINF (-1 * INF)
#define ALL(n) n.begin(),n.end()
#define MOD 1000000007
#define P pair<ll, ll>

ll s[4], ans = INF;
int main() {
	REP(i, 4)cin >> s[i];
	REPO(i, 30) {
		REPO(j, 30) {
			REPO(k, 30) {
				ll dp[100] = {};
				REPO(i, 40)dp[i] = INF;
				REP(l, 30) {
					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[s[0]] + dp[s[1]] + dp[s[2]] + dp[s[3]]);
			}
		}
	}
	cout << ans << endl;
}