#include <iostream>

using namespace std;
int tree[1024*1024];
int k;
int a,b,c;
int power2(int n)
{
    int i=1;
    int j;
    for(j=0; j<n; j++)
        i=i*2;
    return i;
}
int get_xiabiao(int n)
{
    int i,j;
    int xiabiao=-1;
    for(i=0; i<power2(k)-1; i++)
    {
        if(tree[i]==n)
        {
            xiabiao=i;
            break;

        }
    }
    return xiabiao;

}
int get_shendu(int n)
{
    int i=0;
    for(i=0; n; i++)
    {
        n=(n-1)/2;
    }
    return i;

}
int main()
{
    cin>>k>>a>>b>>c;
    int i,j;
    int m;
    for(i=0; i<k; i++)
    {
        int start=power2(k-1-i);
        for(j=power2(i)-1,m=0; j<power2(i+1)-1; j++,m++)
        {
            tree[j]=start+start*2*m;
        }
    }

    int a_xiabiao=get_xiabiao(a);
    int b_xiabiao=get_xiabiao(b);
    int c_xiabiao=get_xiabiao(c);
    int a_shendu=get_shendu(a_xiabiao);
    int b_shendu=get_shendu(b_xiabiao);
    int c_shendu=get_shendu(c_xiabiao);


    int Min=1<<30;
    if(Min>a_shendu)Min=a_shendu;
    if(Min>b_shendu)Min=b_shendu;
    if(Min>c_shendu)Min=c_shendu;

    for(i=0; i<a_shendu-Min; i++)
        a_xiabiao=(a_xiabiao-1)/2;
    for(i=0; i<b_shendu-Min; i++)
        b_xiabiao=(b_xiabiao-1)/2;
    for(i=0; i<c_shendu-Min; i++)
        c_xiabiao=(c_xiabiao-1)/2;

    for(i=0; i<Min; i++)
    {
        if(a_xiabiao==b_xiabiao&&b_xiabiao==c_xiabiao)
        {
            break;
        }
        else
        {
            a_xiabiao=(a_xiabiao-1)/2;
            b_xiabiao=(b_xiabiao-1)/2;
            c_xiabiao=(c_xiabiao-1)/2;
        }
    }
    cout<<tree[a_xiabiao]<<endl;
    return 0;
}

#include <iostream>using namespace std;int k,a,b,c;struct tree{ int data; tree *left; tree *right;};int power2(int n){ int i=1; for(int j=0; j<n; j++) i=i*2; return i;}void create(tree *root,int n){ if(n==k) { root->data=power2(n-1); } if(n==k-2) { tree *tree_left=new tree; tree *tree_right=new tree; root->left=tree_left; root->right=tree_right; tree_left->data=root->data-power2(n-2); tree_right->data=root->data+power2(n-2); return ; } tree *tree_left=new tree; tree *tree_right=new tree; root->left=tree_left; root->right=tree_right; tree_left->data=root->data-power2(n-2); create(root->left,n-1); tree_right->data=root->data+power2(n-2); create(root->right,n-1); return ;}tree *FindParent2(tree*root,tree*a,tree*b){ if(root==NULL) return NULL; if(root==a||root==b) return root; tree*left=FindParent2(root->left,a,b); tree*right=FindParent2(root->right,a,b); if(left&&right) return root; return left?left:right;}tree *FindParent(tree*root,tree*a,tree*b){ int min,max; if(a->data<b->data) { min=a->data,max=b->data; } else { min=b->data,max=a->data; } while(root) { if(root->data>=min&&root->data<=max) return root; else if(root->data<min&&root->data<max) { root=root->right; } else root=root->left; } return NULL;}tree *Find(tree*root,int n){ if(root->data==n) { return root; } else if(root->data<n) { return Find(root->right,n); } return Find(root->left,n);}int main(){ cin>>k>>a>>b>>c; tree *root=new tree; create(root,k); tree *atree=new tree; tree *btree=new tree; tree *ctree=new tree; atree=Find(root,a); btree=Find(root,b); ctree=Find(root,c); tree *abparent=new tree; abparent=FindParent(root,atree,btree); tree *abcparent=new tree; abcparent=FindParent(root,abparent,ctree); cout<<abcparent->data<<endl;/* tree *abparent2=new tree; abparent2=FindParent2(root,atree,btree); tree *abcparent2=new tree; abcparent2=FindParent2(root,abparent2,ctree); cout<<abcparent2->data<<endl;*/ return 0;}