#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
using namespace std;
using ll = long long;
using P = pair<int,int>;

int main(){
	int a,b,c,k;
	cin >> a >> b >> c >> k;
	int mn = max(a,max(b,c));
	int ans = a + b + c - mn + pow(2,k) * mn;
	cout << ans << endl;
}
#include <iostream>
#include <fstream>
#include <set>
#include <map>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <functional>
#include <algorithm>
#include <climits>
#include <cmath>
#include <iomanip>
using namespace std;
#define ll long long int
#define rep(i,n) for( int i = 0; i < n; i++ )
#define rrep(i,n) for( int i = n; i >= 0; i-- )
#define REP(i,s,t) for( int i = s; i <= t; i++ )
#define RREP(i,s,t) for( int i = s; i >= t; i-- )
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define INF 2000000000
#define mod 1000000007
#define INF2 1000000000000000000


int main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int A[3];
    rep(i, 3) cin >> A[i];
    int K; cin >> K;
    sort(A, A + 3);
    rep(i, K) A[2] *= 2;
    cout << A[0] + A[1] + A[2] << endl;
    

    return 0;
}
