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


void main() {
    int n;
    scan(n);
    auto d = readln.split.to!(int[]);
    int x, y;
    scan(x, y);

    long L = abs(x) + abs(y);

    if (L == 0) {
        writeln(0);
        return;
    }

    d.sort();

    foreach (i ; 0 .. n) {
        if (d[i] == L) {
            writeln(1);
            return;
        }
    }

    auto ds = (d.map!(a => -a).retro().array ~ d).assumeSorted();

    debug {
        writeln(ds);
    }

    foreach (i ; 0 .. 2*n) {
        long r = L - ds[i];
        auto lb = ds.lowerBound(r + 1);

        debug {
            writeln(lb);
        }

        if (!lb.empty && lb.back == r) {
            writeln(2);
            return;
        }
    }

    writeln(-1);
}


void scan(T...)(ref T args) {
    string[] line = readln.split;
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}


void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
}