mzp

#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#include <stack>
#include <set>
#include <map>
#define pii pair <int,int>
#define vec vector
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
void cv(vector <int> &v){
    for (auto x: v) cout<<x<<' ';
    cout<<"\n";
}

void cvl(vector <ll> &v){
    for (auto x: v) cout<<x<<' ';
    cout<<"\n";
}


void cvv(vector <vector <int> > &v){
    for (auto x: v) cv(x);
    cout<<"\n";
}

void cvb(vector <bool> v){
    for (bool x: v) cout<<x<<' ';
    cout<<"\n";
}

void cvs(vector <string>  v){
    for (auto a: v){
        cout<<a<<"\n";
    }
}

ll S(int a1, int d, int n){
    return (2*a1 + d * (n - 1)) * n / 2;
}

bool sh=0;


ll N,A,B,C,ans, ans_bef;


ll f(int i, int k){
    return S(A, A, N - 1 - i) + C * (i + 1) + S(B, B, i - k - 1) + S(A, A, k + 1);
}

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


    cin>>N>>A>>B>>C;
    ans=C*N + S(A,A,N) + S(B,B,N);
    for (int i=0;i<N;++i){
        for (int k = 0; k < i; ++k){
            ans = min(ans, f(i,k));
        }
    }
    cout<<ans;
}
/*
6
20
10
5
*/