#include <iostream>
#include <stdio.h>
#include <vector>
#include <string.h>
using namespace std;

int n,k;
int somebody[1000001];
int somechair[1000001];

vector<int> ms;

int main()
{
    freopen("birthday.in","r",stdin);
    freopen("birthday.out","w",stdout);

    int i;
    int a;
    bool first=true;
    int firstchair=0;

    memset(somebody,0,sizeof(somebody));
    memset(somechair,0,sizeof(somechair));

    scanf("%d %d",&n,&k);

    for (i=1;i<=k;i++)
    {
        scanf("%d",&a);
        somechair[a]=i;
    }

    for (i=1;i<=k+1;i++)
    {
        scanf("%d",&a);
        somebody[a]=i;
    }

    for (i=1;i<=n;i++)
    {
        if (somebody[i]!=0)
        {
            ms.push_back(somebody[i]);
        }

        if (somechair[i]!=0)
        {
            if (first)
            {
                first=false;
                firstchair=i;
            }

            if (!ms.empty())
            {
                if (i==firstchair)
                {
                    printf("%d\n",ms.back());
                }

                ms.pop_back();
                somechair[i]=0;
            }
        }
    }

    for (i=1;i<=n;i++)
    {
        if (somechair[i]!=0)
        {
            if (!ms.empty())
            {
                if (i==firstchair)
                {
                    printf("%d\n",ms.back());
                }

                ms.pop_back();
                somechair[i]=0;
            }
        }
    }

    printf("%d\n",ms.back());

    return 0;
}