#pragma GCC optimize("Ofast,unroll-loops")
#include<bits/stdc++.h>
#define int   long long
#define ll long long
#define down cout<<'\n';
#define debug cout<<" cucuucucuuu",down
#define NHP     ios_base::sync_with_stdio(0);cout.tie(0);cin.tie(0);
#define modwwe  int t;cin>>t; while(t--)
#define bit(i,j) (i>>j&1)
#define sobit(a) __builtin_popcountll(a)
#define task "test"
#define fin(x) freopen(x".inp","r",stdin)
#define fou(x) freopen(x".out","w",stdout)
#define pb push_back
#define mask(k) (1<<k)
#define mp make_pair
#define checktime   cerr << (double)clock() / CLOCKS_PER_SEC * 1000  << " ms";
using namespace std;
#define getchar_unlocked getchar

inline int scan()
{
    char c = getchar_unlocked();
    int x = 0;
    while (c < '0' || c > '9')
    {
        c = getchar_unlocked();
    }
    while (c >= '0' && c <= '9')
    {
        x = (x << 1) + (x << 3) + c - '0';
        c = getchar_unlocked();
    }
    return x;
}
void phongbeo();
const int inf = 1e16;
const ll mod2 = 1e9+7;
const int  mod1 = 998244353;
const ll base=67;
int add(int x,int y)
{
    if(x+y>=mod2) x-=mod2;
    if(x+y<0)x+=mod2;
    return x+y;
}
struct icd
{
    long double a;
    int b;
};
struct ib
{
    int a;
    int b;
};
struct ic
{
    ll a;
    int  b, c;
};
struct id
{
    int a, b, c, d;
};
struct ie
{
    int a, b, c, d, e;

};
int n, m, s1, s2, s4, s3, sf, k, s5, s6, mx, s7, s8, s9, mx2, res, dem2 = 0, dem = 0, s33, dem3, dem4, mid, l2, r2, center;
int  i, s10, s12,k1,k2,k3,s11,lim,w,l,r ;
int kk;
int el = 19;
main()
{
    if(fopen(task".inp","r"))
    {
        fin(task);
        fou(task);
    }
    NHP
    ///  cin>>s1;
    // modwwe
    phongbeo();
//   checktime
}
int c[100000];
int a[100000];
vector<int> v,ke[200001],v2;
int dp[200001];
void dfs(int x,int cost)
{
    if(x<=n)
    {
        if(c[x]==0)
        {
            dp[x]=1;
        }
        else
        {
            if(c[x]>=cost)dp[x]=0;
            else dp[x]=inf;
        }
    }
    else
    {
        int mx1=inf,mx2=inf;
        for(auto f:ke[x])
        {
            dfs(f,cost);
            if(dp[f]<mx1)mx2=mx1,mx1=dp[f];
            else if(dp[f]<mx2)mx2=dp[f];
        }
        dp[x]=mx1+mx2;
    }
}
bool check(int x)
{
    dem=0;
    for(int i=1; i<=m; i++)
        if(a[i]>=x)dem++;
    dfs(dem2,x);
    return dp[dem2]<=dem;
}
void phongbeo()
{
    cin>>n>>m;
    for(int i=1; i<=m; i++)
    {
        cin>>l>>r;
        c[r]=l;
        v2.pb(l);
    }
    m=n-m;
    for(int i=1; i<=m; i++)
        cin>>a[i],v2.pb(a[i]);
    l=1;
    dem=n;
    for(int i=1; i<=n; i++)
        v.pb(i);
    while(v.size()-l!=0)
    {
        ke[++dem].pb(v[l-1]);
        ke[dem].pb(v[l]);
        ke[dem].pb(v[l+1]);
        v.pb(dem);
        l+=3;
    }
    dem2=dem;
   sort(v2.begin(),v2.end());
    l=1;
    r=n-1;
    while(l<=r)
    {
        int mid=l+r>>1;
        if(check(v2[mid]))l=mid+1;
        else r=mid-1;
    }
    cout<<v2[l-1];
}