#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define vt vector
#define pb push_back
#define pii pair<int, int>
#define sz(dq) (int)dq.size()
#define forr(i, a, b) for(int i = a; i < b; i++)
#define fi first
#define se second
#define pll pair<ll, ll>
#define mpp make_pair
#define ALL(v) v.begin(), v.end()
#define ALLR(v) v.rbegin(), v.rend()
#define ld long double
const int mxn = 5e5 + 5;
int n, m;
int d[mxn + 1];
vt<int>adj[mxn + 1];
void solve(){   
    cin >> n >> m;
    for(int i = 1; i <= n; i++)cin >> d[i];
    for(int i = 0; i < m; i++){
        int u, v; cin >> u >> v;
        adj[u].pb(v); adj[v].pb(u);
    }
    for(int i = 1; i <= n; i++){
        if(d[i] == 0){
            bool bad = 0;
            for(auto j: adj[i]){
                if(d[j] != 1){
                    bad = 1; break;
                }
            }
            if(!bad){
                cout << i; return;
            }
        }
    }
}
 
signed main(){
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    //freopen("ARRAY.inp", "r", stdin);
    //freopen("ARRAY.out", "w", stdout);
    
    int tt; tt = 1;
    while(tt--){
        solve();
    }
    return(0);
}