// Standard I/O
#include <iostream>
#include <sstream>
#include <cstdio>
// Standard Library
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <cmath>
// Template Class
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <stack>
// Container Control
#include <algorithm>

using namespace std;

#define rep( i, n ) for( int i = 0; i < n; ++i )
#define irep( i, n ) for( int i = n-1; i >= 0; --i )
#define reep( i, s, n ) for ( int i = s; i < n; ++i )
#define ireep( i, n, s ) for ( int i = n-1; i >= s; --i )
#define foreach(itr, x) for( typeof(x.begin()) itr = x.begin(); itr != x.end(); ++itr)

#define mp make_pair
#define mt make_tuple
#define pb push_back
#define eb emplace_back
#define all( v ) v.begin(), v.end()
#define fs first
#define sc second
#define vc vector

// for visualizer.html
double SCALE = 1.0;
double OFFSET_X = 0.0;
double OFFSET_Y = 0.0;
#define LINE(x,y,a,b) cerr << "line(" << SCALE*(x) + OFFSET_X << ","	\
	<< SCALE*(y) + OFFSET_Y << ","										\
	<< SCALE*(a) + OFFSET_X << ","										\
	<< SCALE*(b) + OFFSET_Y << ")" << endl;
#define CIRCLE(x,y,r) cerr << "circle(" << SCALE*(x) + OFFSET_X << ","	\
	<< SCALE*(y) + OFFSET_Y << ","										\
	<< SCALE*(r) << ")" << endl;

typedef long long ll;
typedef complex<double> Point;

typedef pair<int, int> pii;
typedef pair<int, pii> ipii;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector< vector<int> > vii;
typedef vector< vector<double> > vdd;

typedef vector<int>::iterator vi_itr;

const int IINF = 1 << 28;
const int MOD = 1e9+7;
const double INF = 1e30;
const double EPS = 1e-10;
const double PI = acos(-1.0);

// Direction : L U R D
const int dx[] = { -1, 0, 1, 0};
const int dy[] = { 0, -1, 0, 1 };

int n, m;
int a[128], b[128];
int k;
int c[20], d[20];

int count ( int s[20] ) {
    int cnt = 0;

    int dish[128] = {};
    rep(i, k) {
        if ( s[i] == 0 ) ++dish[c[i]];
        else ++dish[d[i]];
    }

    rep(i, m) {
        if ( dish[a[i]] >= 1 && dish[b[i]] >= 1 ) ++cnt;
    }

    return cnt;
}

int solve ( int s[20], int depth = 0 ) {
    if ( depth == k ) {
        return count(s);
    }

    int ans = 0;
    rep(i, 2) {
        s[depth] = i;
        ans = max(ans, solve(s, depth+1));
    }

    return ans;
}

int main()
{
    cin >> n >> m;
    rep(i, m) cin >> a[i] >> b[i];
    cin >> k;
    rep(i, k) cin >> c[i] >> d[i];

    int s[20] = {};
    int ans = solve(s);
    cout << ans << endl;
}

#include <bits/stdc++.h>
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define drep(i,j,n) for(int i=0;i<(int)(n-1);i++)for(int j=i+1;j<(int)(n);j++)
#define trep(i,j,k,n) for(int i=0;i<(int)(n-2);i++)for(int j=i+1;j<(int)(n-1);j++)for(int k=j+1;k<(int)(n);k++)
#define codefor int test;scanf("%d",&test);while(test--)
#define INT(...) int __VA_ARGS__;in(__VA_ARGS__)
#define LL(...) ll __VA_ARGS__;in(__VA_ARGS__)
#define yes(ans) if(ans)printf("yes\n");else printf("no\n")
#define Yes(ans) if(ans)printf("Yes\n");else printf("No\n")
#define YES(ans) if(ans)printf("YES\n");else printf("NO\n")
#define vector1d(type,name,...) vector<type>name(__VA_ARGS__)
#define vector2d(type,name,h,...) vector<vector<type>>name(h,vector<type>(__VA_ARGS__))
#define vector3d(type,name,h,w,...) vector<vector<vector<type>>>name(h,vector<vector<type>>(w,vector<type>(__VA_ARGS__)))
#define umap unordered_map
#define uset unordered_set
using namespace std;
using ll = long long;
const int MOD=1000000007;
const int MOD2=998244353;
const int INF=1<<30;
const ll INF2=(ll)1<<60;
//入力系
void scan(int& a){scanf("%d",&a);}
void scan(long long& a){scanf("%lld",&a);}
template<class T,class L>void scan(pair<T, L>& p){scan(p.first);scan(p.second);}
template<class T> void scan(T& a){cin>>a;}
template<class T> void scan(vector<T>& vec){for(auto&& it:vec)scan(it);}
void in(){}
template <class Head, class... Tail> void in(Head& head, Tail&... tail){scan(head);in(tail...);}
//出力系
void print(const int& a){printf("%d",a);}
void print(const long long& a){printf("%lld",a);}
void print(const double& a){printf("%.15lf",a);}
template<class T,class L>void print(const pair<T, L>& p){print(p.first);putchar(' ');print(p.second);}
template<class T> void print(const T& a){cout<<a;}
template<class T> void print(const vector<T>& vec){if(vec.empty())return;print(vec[0]);for(auto it=vec.begin();++it!= vec.end();){putchar(' ');print(*it);}}
void out(){putchar('\n');}
template<class T> void out(const T& t){print(t);putchar('\n');}
template <class Head, class... Tail> void out(const Head& head,const Tail&... tail){print(head);putchar(' ');out(tail...);}
//デバッグ系
template<class T> void dprint(const T& a){cerr<<a;}
template<class T> void dprint(const vector<T>& vec){if(vec.empty())return;cerr<<vec[0];for(auto it=vec.begin();++it!= vec.end();){cerr<<" "<<*it;}}
void debug(){cerr<<endl;}
template<class T> void debug(const T& t){dprint(t);cerr<<endl;}
template <class Head, class... Tail> void debug(const Head& head, const Tail&... tail){dprint(head);cerr<<" ";debug(tail...);}
ll intpow(ll a, ll b){ ll ans = 1; while(b){ if(b & 1) ans *= a; a *= a; b /= 2; } return ans; }
ll modpow(ll a, ll b, ll p){ ll ans = 1; while(b){ if(b & 1) (ans *= a) %= p; (a *= a) %= p; b /= 2; } return ans; }
ll modinv(ll a, ll m) {ll b = m, u = 1, v = 0;while (b) {ll t = a / b;a -= t * b; swap(a, b);u -= t * v; swap(u, v);}u %= m;if (u < 0) u += m;return u;}
ll updivide(ll a,ll b){if(a%b==0) return a/b;else return (a/b)+1;}
template<class T> void chmax(T &a,const T b){if(b>a)a=b;}
template<class T> void chmin(T &a,const T b){if(b<a)a=b;}

int main(){
    INT(n,m);
    vector<int> a(n);
    vector<int> minv(n,INF);
    in(a);
    vector<vector<int>> graph(n);
    int from,to,x,ans=-INF;
    rep(i,m){
        in(from,to);
        graph[from-1].push_back(to-1);
    }
    rep(i,n){
        rep(j,graph[i].size()){
            chmin(minv[graph[i][j]],a[i]);
            chmin(minv[graph[i][j]],minv[i]);
        }
    }
    rep(i,n)if(minv[i]!=INF)chmax(ans,a[i]-minv[i]);
    out(ans);
}