#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <queue>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <cctype>
#include <cassert>
#include <limits>
#include <functional>
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
#if defined(_MSC_VER) || __cplusplus > 199711L
#define aut(r,v) auto r = (v)
#else
#define aut(r,v) __typeof(v) r = (v)
#endif
#define each(it,o) for(aut(it, (o).begin()); it != (o).end(); ++ it)
#define all(o) (o).begin(), (o).end()
#define pb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset(m,v,sizeof(m))
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
using namespace std;
typedef vector<int> vi; typedef pair<int,int> pii; typedef vector<pair<int,int> > vpii; typedef long long ll;
template<typename T, typename U> inline void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> inline void amax(T &x, U y) { if(x < y) x = y; }

int main() {
	const int X = 30;
	int V[4];
	while(cin >> V[0] >> V[1] >> V[2] >> V[3]) {
		int dp[31];
		int ans = INF;
		rer(a, 1, X) rer(b, 1, a-1) rer(c, 1, b-1) {
			rer(i, 0, X) dp[i] = INF;
			dp[0] = 0;
			rer(i, 0, X) {
				int x = dp[i];
				if(x == INF) continue;
				if(i + a <= X) amin(dp[i + a], x + 1);
				if(i + b <= X) amin(dp[i + b], x + 1);
				if(i + c <= X) amin(dp[i + c], x + 1);
			}
			int sum = 0;
			rep(i, 4) {
				if(dp[V[i]] == INF) {
					sum = INF;
					break;
				}
				sum += dp[V[i]];
			}
			amin(ans, sum);
		}
		printf("%d\n", ans);
	}
	return 0;
}