#include <bits/stdc++.h>
#define REP(i,n) for (int i = 0; i <(n); ++i)
#define REP2(i,x,n) for (int i = x; i <(n); ++i)
#define ALL(v) v.begin(), v.end()
#define RALL(v) v.rbegin(), v.rend()
using namespace std;
using ll = long long;
using P = pair<int,int>;
static const double PI = acos(-1);
static const int INF = 1e9+7;
#define REP(i,n) for (int i = 0; i <(n); ++i)
//debug 
#ifdef _DEBUG
#define debug(var)  do{cout << #var << " :";view(var);}while(0)
#else
#define debug(...)
#endif
template<typename T> void view(T e){cout << e << endl;}
template<typename T> void view(const vector<T>& v){for(const auto& e : v){ cout << e << " "; } cout << endl;}
template<typename T> void view(const vector<vector<T> >& vv){ for(const auto& v : vv){ view(v); } }


int main(){
  int a, b, c;
  cin >> a >> b >> c;
  int k;
  cin >> k;

  if(c > b) swap(b,c);
  if(b > a) swap(a,b);
  if(c > b) swap(b,c);

  // cout << a << b << c;
  REP(i,k){
    a *= 2;
  }

  int ans = a + b + c;
  cout << ans << endl;



  return 0;
}
#include<bits/stdc++.h>
#define ll long long
#define pii_ pair<int,int>
#define mp_ make_pair
#define pb push_back
#define fi first
#define se second
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
#define show1(a) cout<<#a<<" = "<<a<<endl
#define show2(a,b) cout<<#a<<" = "<<a<<"; "<<#b<<" = "<<b<<endl
using namespace std;
const ll INF = 1LL<<60;
const int inf = 1<<30;
const int maxn = 2e5+5;
inline void fastio() {ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);}



int main()
{
    fastio();
    int a,b,c;
    cin>>a>>b>>c;
    cout<<min(min(a+b,b+c),a+c)<<endl;
    return 0;
}
