/+ dub.sdl:
    name "A"
    dependency "dcomp" version=">=0.7.4"
+/
 
import std.stdio, std.conv, std.algorithm, std.range;
import std.math;

// import dcomp.scanner;

int solve() {
    auto sc = new Scanner(stdin);
    int n;
    long[] _di;
    sc.read(n, _di);
    typeof(_di.sort!"a<b")[2] di;
    di[0] = _di.filter!"a%2==0".array.sort!"a<b";
    di[1] = _di.filter!"a%2==1".array.sort!"a<b";
    long x, y;
    sc.read(x, y);
    if (x == 0 && y == 0) {
        return 0;
    }
    long dist = abs(x) + abs(y);
    if (di[0].contains(dist) || di[1].contains(dist)) {
        return 1;
    }

    foreach (d; _di) {
        long mi = 10L^^18;
        long ma = -(10L^^18);
        void ck(long a, long b) {
            long c = abs(a) + abs(b);
            mi = min(mi, c);
            ma = max(ma, c);
        }
        ck(x-d, y);
        ck(x+d, y);
        ck(x, y-d);
        ck(x, y+d);
        if (y-x-d <= 0 && 0 <= y-x+d) {
            long z = (y-x+d)/2;
            ck(x-d+z, y-z);
        }
        if (y+x-d <= 0 && 0 <= y+x+d) {
            long z = (y+x+d)/2;
            ck(x+d-z, y-z);
        }
        auto rng = di[(mi%2+2)%2].upperBound(mi-1);
        if (!rng.empty && rng.front <= ma) {
            return 2;
        }
    }
    return -1;
}

void main() {
    writeln(solve());
}
/* IMPORT /home/yosupo/Program/dcomp/source/dcomp/scanner.d */
// module dcomp.scanner;

// import dcomp.container.stack;

 
class Scanner {
    import std.stdio : File;
    import std.conv : to;
    import std.range : front, popFront, array, ElementType;
    import std.array : split;
    import std.traits : isSomeChar, isStaticArray, isArray; 
    import std.algorithm : map;
    File f;
    this(File f) {
        this.f = f;
    }
    char[512] lineBuf;
    char[] line;
    private bool succW() {
        import std.range.primitives : empty, front, popFront;
        import std.ascii : isWhite;
        while (!line.empty && line.front.isWhite) {
            line.popFront;
        }
        return !line.empty;
    }
    private bool succ() {
        import std.range.primitives : empty, front, popFront;
        import std.ascii : isWhite;
        while (true) {
            while (!line.empty && line.front.isWhite) {
                line.popFront;
            }
            if (!line.empty) break;
            line = lineBuf[];
            f.readln(line);
            if (!line.length) return false;
        }
        return true;
    }

    private bool readSingle(T)(ref T x) {
        import std.algorithm : findSplitBefore;
        import std.string : strip;
        import std.conv : parse;
        if (!succ()) return false;
        static if (isArray!T) {
            alias E = ElementType!T;
            static if (isSomeChar!E) {
                 
                 
                auto r = line.findSplitBefore(" ");
                x = r[0].strip.dup;
                line = r[1];
            } else static if (isStaticArray!T) {
                foreach (i; 0..T.length) {
                    bool f = succW();
                    assert(f);
                    x[i] = line.parse!E;
                }
            } else {
                StackPayload!E buf;
                while (succW()) {
                    buf ~= line.parse!E;
                }
                x = buf.data;
            }
        } else {
            x = line.parse!T;
        }
        return true;
    }
    int read(T, Args...)(ref T x, auto ref Args args) {
        if (!readSingle(x)) return 0;
        static if (args.length == 0) {
            return 1;
        } else {
            return 1 + read(args);
        }
    }
}


 
 

 
/* IMPORT /home/yosupo/Program/dcomp/source/dcomp/container/stack.d */
// module dcomp.container.stack;

struct StackPayload(T, size_t MIN = 4) {
    import std.algorithm : max;
    import std.conv;
    import std.range.primitives : ElementEncodingType;
    import core.stdc.string : memcpy;

    private T* _data;
    private uint len, cap;
     
    bool empty() const { return len == 0; }
    @property size_t length() const { return len; }
    alias opDollar = length;

    ref inout(T) opIndex(size_t i) inout { return _data[i]; }
    ref inout(T) front() inout { return _data[0]; }
    ref inout(T) back() inout { assert(len); return _data[len-1]; }
    
     
    void reserve(size_t nlen) {
        import core.memory : GC;
        if (nlen <= cap) return;
        
        void* nx = GC.malloc(nlen * T.sizeof);

        cap = nlen.to!uint;
        if (len) memcpy(nx, _data, len * T.sizeof);
        _data = cast(T*)(nx);
    }
    void free() {
        import core.memory : GC;
        GC.free(_data);
    }
     
    void opOpAssign(string op : "~")(T item) {
        if (len == cap) {
            reserve(max(MIN, cap*2));
        }
        _data[len++] = item;
    }
     
    void insertBack(T item) {
        this ~= item;
    }
     
    void removeBack() {
        len--;
    }
     
    void clear() {
        len = 0;
    }
     
    T[] data() {
        return (_data) ? _data[0..len] : null;
    }
}

 

 

/*
This source code generated by dcomp and include dcomp's source code.
dcomp's Copyright: Copyright (c) 2016- Kohei Morita. (https://github.com/yosupo06/dcomp)
dcomp's License: MIT License(https://github.com/yosupo06/dcomp/blob/master/LICENSE.txt)
*/