#include <bits/stdc++.h>
using namespace std;
#define GET_MACRO(_1, _2, _3, NAME, ...) NAME
#define _repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define _rep(i,n) _repl(i,0,n)
#define rep(...) GET_MACRO(__VA_ARGS__, _repl, _rep)(__VA_ARGS__)
#define mp(a,b) make_pair((a),(b))
#define pb(a) push_back((a))
#define all(x) (x).begin(),(x).end()
#define uniq(x) sort(all(x)),(x).erase(unique(all(x)),end(x))
#define fi first
#define se second
#define dbg(...) _dbg(#__VA_ARGS__, __VA_ARGS__)
void _dbg(string){cout<<endl;}
template<class H,class... T> void _dbg(string s,H h,T... t){int l=s.find(',');cout<<s.substr(0,l)<<" = "<<h<<", ";_dbg(s.substr(l+1),t...);}
template<class T,class U> ostream& operator<<(ostream &o, const pair<T,U> &p){o<<"("<<p.fi<<","<<p.se<<")";return o;}
template<class T> ostream& operator<<(ostream &o, const vector<T> &v){o<<"[";for(T t:v){o<<t<<",";}o<<"]";return o;}

int solve(){
  int n;
  cin>>n;
  vector<long> v(n);
  rep(i,n) cin>>v[i];

  long x,y;
  cin>>x>>y;
  long goal = abs(x) + abs(y);

  if(x==0 && y==0) return 0;
  rep(i,n) if(v[i] == goal) return 1;

  vector<vector<long>> vv(2);
  rep(i,n) vv[v[i]%2].pb(v[i]);
  sort(all(vv[0]));
  sort(all(vv[1]));

  if(goal%2==0){
    rep(i,2){
      int s = vv[i].size();
      if(s>=2 && vv[i][s-1] + vv[i][s-2] >= goal) return 2;
    }
  }
  else{
    if(vv[0].size()>0 && vv[1].size()>0 && vv[0].back() + vv[1].back() >= goal) return 2;
  }

  return -1;
}

int main(){
  cout << solve() << endl;

  return 0;
}