#include<bits/stdc++.h>
#define rep(i,a,...) for(int i = (a)*(strlen(#__VA_ARGS__)!=0);i<(int)(strlen(#__VA_ARGS__)?__VA_ARGS__:(a));++i)
#define per(i,a,...) for(int i = (strlen(#__VA_ARGS__)?__VA_ARGS__:(a))-1;i>=(int)(strlen(#__VA_ARGS__)?(a):0);--i)
#define foreach(i, n) for(auto &i:(n))
#define pii pair<int, int>
#define pll pair<long long, long long>
#define all(x) (x).begin(), (x).end()
#define bit(x) (1ll << (x))
using ll = long long;
//const ll MOD = (ll)1e9+7;
const ll MOD = 998244353;
const int INF = (ll)1e9+7;
const ll INFLL = (ll)1e18;
using namespace std;
template<class t>
using vvector = vector<vector<t>>;
template<class t>
using vvvector = vector<vector<vector<t>>>;
template<class t>
using priority_queuer = priority_queue<t, vector<t>, greater<t>>;
template<class t, class u> bool chmax(t &a, u b){if(a<b){a=b;return true;}return false;}
template<class t, class u> bool chmin(t &a, u b){if(a>b){a=b;return true;}return false;}
#ifdef DEBUG
#define debug(x) cout<<"LINE "<<__LINE__<<": "<<#x<<" = "<<x<<endl;
#else
#define debug(x) (void)0
#endif

ll modpow(ll x, ll b){
  ll res = 1;
  while(b){
    if(b&1)res = res * x % MOD;
    x = x * x % MOD;
    b>>=1;
  }
  return res;
}

ll modinv(ll x){
  return modpow(x, MOD-2);
}

bool was_output = false;
template<class t>
void output(t a){
  if(was_output)cout << " ";
  cout << a;
  was_output = true;
}
void outendl(){
  was_output = false;
  cout << endl;
}
ll in(){
  ll res;
  scanf("%lld", &res);
  return res;
}

template<class t>
istream& operator>>(istream&is, vector<t>&x){
  for(auto &i:x)is >> i;
  return is;
}

template<class t, class u>
istream& operator>>(istream&is, pair<t, u>&x){
  is >> x.first >> x.second;
  return is;
}

template<class t>
void in(t&x){
  cin >> x;
}

int main(){
  vector<int> line(4);
  cin>>line;
  sort(all(line));
  int sum = line[0] + line[3] - line[1] - line[2];
  cout << abs(sum) << endl;
  return 0;
}

