#include <bits/stdc++.h>
using namespace std;

using Int32 = int_fast32_t;
using Word32 = uint_fast32_t;
using Int64 = int_fast64_t;
using Word64 = uint_fast64_t;
using Int128 = __int128_t;
using Word128 = __uint128_t;
using Int = int_fast64_t;
using Word = uint_fast64_t;
using F32 = float;
using F64 = double;
using F80 = long double;
using VInt = vector<Int>;
using VVI = vector<VInt>;
using VWord = vector<Word>;
using VVW = vector<VWord>;
using VF32 = vector<F32>;
using VF64 = vector<F64>;
using VF80 = vector<F80>;
using VS = vector<string>;
using VVS = vector<VS>;
using VB = vector<bool>;
using VVB = vector<VB>;
using PII = pair<Int,Int>;
using PWW = pair<Word,Word>;
using VPII = vector<PII>;
using VPWW = vector<PWW>;
using PQ_PII = priority_queue<PII, VPII, greater<PII>>;

#define SZ(x) ((Int)(x).size())
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end())
#define rep(i,n) for(Int i=0, i##_len=(n); i<i##_len; ++i)
#define reps(i,n) for(Int i=0, i##_len=(n); i<=i##_len; ++i)
#define Range(i,a,b) for(Int i=(a); i<=(Int)(b); i++)
#define ALL(x) (x).begin(),(x).end()
#define RALL(x) (x).rbegin(),(x).rend()
#define pb push_back
#define eb emplace_back
#define mp make_pair

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  Int v[4];
  rep(i,4) cin >> v[i];
  const Int maxv = 31;
  Int ans = 10000;

  for (Int a = 1; a < maxv; a++) {
    for (Int b = a + 1; b < maxv; b++) {
      for (Int c = b + 1; c < maxv; c++) {
        VInt dp(maxv, 10000);
        dp[0] = 0;
        for (Int i = 0; i < maxv - a; i++) dp[i + a] = min(dp[i + a], dp[i] + 1);
        for (Int i = 0; i < maxv - b; i++) dp[i + b] = min(dp[i + b], dp[i] + 1);
        for (Int i = 0; i < maxv - c; i++) dp[i + c] = min(dp[i + c], dp[i] + 1);
        ans = min(ans, dp[v[0]] + dp[v[1]] + dp[v[2]] + dp[v[3]]);
      }
    }
  }
  return 0;
}