#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i=0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)
using ll = long long;
using VL = vector<ll>;
using VVL = vector<vector<ll>>;
using P = pair<ll, ll>;

// chmin, chmax関数
template<typename T, typename U, typename Comp=less<>>
bool chmax(T& xmax, const U& x, Comp comp={}) {
    if(comp(xmax, x)) {
        xmax = x;
        return true;
    }
    return false;
}
template<typename T, typename U, typename Comp=less<>>
bool chmin(T& xmin, const U& x, Comp comp={}) {
    if(comp(x, xmin)) {
        xmin = x;
        return true;
    }
    return false;
}

// modint: mod 計算を int を扱うように扱える構造体
template<int MOD> struct Fp {
    long long val;
    constexpr Fp(long long v = 0) noexcept : val(v % MOD) {
        if (val < 0) val += MOD;
    }
    constexpr int getmod() { return MOD; }
    constexpr Fp operator - () const noexcept {
        return val ? MOD - val : 0;
    }
    constexpr Fp operator + (const Fp& r) const noexcept { return Fp(*this) += r; }
    constexpr Fp operator - (const Fp& r) const noexcept { return Fp(*this) -= r; }
    constexpr Fp operator * (const Fp& r) const noexcept { return Fp(*this) *= r; }
    constexpr Fp operator / (const Fp& r) const noexcept { return Fp(*this) /= r; }
    constexpr Fp& operator += (const Fp& r) noexcept {
        val += r.val;
        if (val >= MOD) val -= MOD;
        return *this;
    }
    constexpr Fp& operator -= (const Fp& r) noexcept {
        val -= r.val;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr Fp& operator *= (const Fp& r) noexcept {
        val = val * r.val % MOD;
        return *this;
    }
    constexpr Fp& operator /= (const Fp& r) noexcept {
        long long a = r.val, b = MOD, u = 1, v = 0;
        while (b) {
            long long t = a / b;
            a -= t * b; swap(a, b);
            u -= t * v; swap(u, v);
        }
        val = val * u % MOD;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr bool operator == (const Fp& r) const noexcept {
        return this->val == r.val;
    }
    constexpr bool operator != (const Fp& r) const noexcept {
        return this->val != r.val;
    }
    friend constexpr ostream& operator << (ostream &os, const Fp<MOD>& x) noexcept {
        return os << x.val;
    }
    friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept {
        if (n == 0) return 1;
        auto t = modpow(a, n / 2);
        t = t * t;
        if (n & 1) t = t * a;
        return t;
    }
};


const int MOD = 1000000007;
using mint = Fp<MOD>;
//---------------------------

int main(){
    ll n;
    cin >> n;
    VL a(n);
    rep(i,n) cin >> a[i];

    bool flag = true;

    if(n%2 == 0){
        ll k = n/2;
        VL b(k,0);
        rep(i,n){
            if(a[i]%2==0) flag = false;
            else if(a[i] > 2*k-1) flag = false;
            else b[a[i]/2]++;
        }
        rep(i,k){
            if(b[i] != 2) flag = false;
        }
        if(flag){
            mint pow2 = 1;
            rep(i,k) pow2 *= (mint)2;
            cout << pow2 << endl;
        }else{
            cout << 0 << endl;
        }
    }else{
        ll k = n/2, n0 = 0;
        VL b(k,0);
        rep(i,n){
            if(a[i]%2==1) flag = false;
            else if(a[i] > 2*k) flag = false;
            else if(a[i]==0) n0++;
            else b[a[i]/2 - 1]++;
        }
        if(n0 != 1) flag = false;
        if(flag){
            mint pow2 = 1;
            rep(i,k) pow2 *= (mint)2;
            cout << pow2 << endl;
        }else{
            cout << 0 << endl;
        }
    }

    return 0;
}

Measured memory_bytes: 1408