#include <bits/stdc++.h>
#define ll long long int
#define yorn(f) cout<<((f)?"Yes":"No")<<endl;
#define YORN(f) cout<<((f)?"YES":"NO")<<endl;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repi(i, n) for (int i = 1; i < (int)(n); i++)
#define all(x) (x).begin(), (x).end()
#define put(x) cout << x << endl;
#define println(x) cout << x << endl;
using namespace std;
int main()
{
    int n, k;
    cin >> n >> k;
    int v = 1;
    rep(i, n) {
        v = min(v * 2, v + k);
    }
    put(v)
    
    return 0;
}
#include <bits/stdc++.h>
#include <math.h>
using namespace std;
typedef long long ll;
typedef vector<int> vint;
#define rep(i,n) for (ll i = 0; i < (ll)(n); ++i)
#define rrep(i,j,n) for(ll i = (ll)(j); i < (ll)(n); i++)
#define mrep(i,n) for (ll i = (ll)(n-1); i > 0; i--)
#define be(v) (v).begin(), (v).end()
#define scout cout << fixed << setprecision(20) 
ll INF = 1LL << 60;
ll mod = 1e9 + 7;

int main() {
	vint a(3);
	rep(i,3) cin >> a[i];
	int k; cin >> k;
	sort(be(a));
	rep(i,k) a[2]=a[2]*2;
	cout << a[0]+a[1]+a[2] << endl;
}