import std.algorithm, std.conv, std.range, std.stdio, std.string;
import std.math;      // math functions

void main()
{
  auto n = readln.chomp.to!int;
  auto d = readln.split.to!(int[]);
  auto rd = readln.split.to!(int[]), x = rd[0].abs, y = rd[1].abs, d1 = x + y;

  auto ds = d.sort();

  if (ds.contains(d1)) {
    writeln(1);
    return;
  }

  foreach (di; d) {
    auto d2 = (d1 - di).abs;
    if (ds.contains(d2)) {
      writeln(2);
      return;
    }
  }

  writeln(-1);
}