import std.conv, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.container, std.math, std.numeric, std.range, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(T)(in T[] as, in bool delegate(T) test) { int low = -1, upp = cast(int)(as.length); for (; low + 1 < upp; ) { int mid = (low + upp) >> 1; (test(as[mid]) ? low : upp) = mid; } return upp; }
int lowerBound(T)(in T[] as, in T val) { return as.binarySearch((T a) => (a < val)); }
int upperBound(T)(in T[] as, in T val) { return as.binarySearch((T a) => (a <= val)); }


int N;
long[] D;
long X, Y;

int solve() {
  D.sort;
  if (X < 0) {
    X = -X;
  }
  if (Y < 0) {
    Y = -Y;
  }
  
  if (X == 0 && Y == 0) {
    return 0;
  }
  
  foreach (i; 0 .. N) {
    if (X + Y == D[i]) {
      return 1;
    }
  }
  
  auto dss = new long[][2];
  foreach (i; 0 .. N) {
    dss[cast(int)(D[i] % 2)] ~= D[i];
  }
  
  foreach (i; 0 .. N) {
    alias Pt = Tuple!(long, "x", long, "y");
    foreach (h; 0 .. 2) {
      Pt[] ps;
      switch (h) {
        case 0: {
          ps ~= Pt(-D[i], 0L);
          ps ~= Pt(0L, +D[i]);
          ps ~= Pt(+D[i], 0L);
          if (0 < X && X < +D[i]) {
            ps ~= Pt(X, D[i] - X);
          }
          if (0 < Y && Y < +D[i]) {
            ps ~= Pt(D[i] - Y, Y);
          }
        } break;
        case 1: {
          ps ~= Pt(-D[i], 0L);
          ps ~= Pt(0L, -D[i]);
          ps ~= Pt(+D[i], 0L);
          if (0 < X && X < +D[i]) {
            ps ~= Pt(X, -(D[i] - X));
          }
        } break;
        default: assert(false);
      }
      ps.sort;
      debug {
        writeln(D[i], " ", h, " ", ps);
      }
      foreach (j; 1 .. ps.length) {
        long dMin = abs(ps[j - 1].x - X) + abs(ps[j - 1].y - Y);
        long dMax = abs(ps[j    ].x - X) + abs(ps[j    ].y - Y);
        if (dMin > dMax) {
          swap(dMin, dMax);
        }
        debug {
          writeln(D[i], " ", h, " [", dMin, ", ", dMax, "]");
        }
        const ds = dss[cast(int)(dMin % 2)];
        const pos = ds.lowerBound(dMin);
        if (pos < ds.length && ds[pos] <= dMax) {
          return 2;
        }
      }
    }
  }
  
  return -1;
}

void main() {
  try {
    for (; ; ) {
      N = readInt();
      D = new long[N];
      foreach (i; 0 .. N) {
        D[i] = readLong();
      }
      X = readLong();
      Y = readLong();
      const ans = solve();
      writeln(ans);
    }
  } catch (EOFException e) {
  }
}