#include <bits/stdc++.h>
using namespace std;
const int maxn = 10000 + 10;
int In_order[maxn], Post_order[maxn], lch[maxn], rch[maxn];
int tot, cnt;
//[L1,R1] , [L2,R2];
bool read(int* a){
    string t;
    if(!getline(cin, t))
        return false;
    int n = 0, x;
    stringstream ss(t);
    while(ss >> x) a[n++] = x;

    tot = n;
    if(n == 0) return false;
    else return true;
}
int bulid(int L1, int R1, int L2, int R2){
    if(R1 < L1) { return 0;}
    int root = Post_order[R2];
    int p = L1;
    while(In_order[p] != root) p++;
    int  pcnt = p - L1;
    lch[root] =  bulid(L1, p-1,L2, L2 + pcnt -1);
    rch[root] =  bulid(p+1, R1,L2 + pcnt, R2 - 1);
    return root;
}
int best_sum = 1e9, best;
void dfs(int u, int sum)
{
    sum += u;
    if(!lch[u] && !rch[u]){
        if(sum < best_sum || (sum == best_sum && u < best)){
            best = u; best_sum = sum;
        }
    }
    if(lch[u]){
        dfs(lch[u],sum);
    }
    if(rch[u]){
        dfs(rch[u],sum);
    }
}
int main(){
    while(read(In_order)){
        memset(lch,0,sizeof(lch));
        memset(rch,0,sizeof(rch));
        best_sum = 1e9, best = 0;
        read(Post_order);
        cnt = 0;
        bulid(0,tot-1,0,tot-1);
        dfs(Post_order[tot-1],0);
        printf("%d\n", best);
    }
    return 0;
}