#include "bits/stdc++.h"
#define ALL(obj) (obj).begin(),(obj).end()
#define RALL(obj) (obj).rbegin(),(obj).rend()
#define REP(i, n) for(int i = 0; i < (int)(n); i++)
#define REPR(i, n) for(int i = (int)(n); i >= 0; i--)
#define FOR(i,n,m) for(int i = (int)(n); i < int(m); i++)
using namespace std;
typedef long long ll;
const int MOD = 1e9 + 7;
const int INF = MOD - 1;
const ll LLINF = 4e18;

int main() {
    int v[4],ans = INF;
    REP(i, 4) cin >> v[i];
    // 1<=a<b<c<=30
    FOR(a,1, 29) {
        FOR(b,a+1, 30) {
            FOR(c, b+1, 31) {
                //dp[i]:a,b,cをつかってiを作るときの最小数
                vector<int> dp(31, INF);
                dp[0] = 0;
                REP(i, 31) {
                    if (i >= a) dp[i] = min(dp[i], dp[i - a] + 1);
                    if (i >= b) dp[i] = min(dp[i], dp[i - b] + 1);
                    if (i >= c) dp[i] = min(dp[i], dp[i - c] + 1);
                }
                int sum = 0;
                REP(i, 4) {
                    if (dp[v[i]] == INF) {
                        sum = INF;
                        break;
                    }
                    sum += dp[v[i]];
                }
                ans = min(ans, sum);
            }
        }
    }
    cout << ans << endl;
    getchar(); getchar();
}