#include "bits/stdc++.h"
using namespace std;
#define Rep(i,n) for(int i=0;i<(int)(n);i++)
#define For(i,n1,n2) for(int i=(int)(n1);i<(int)(n2);i++)
#define REP(i,n) for(ll i=0;i<(ll)(n);i++)
#define RREP(i,n) for(ll i=((ll)(n)-1);i>=0;i--)
#define FOR(i,n1,n2) for(ll i=(ll)(n1);i<(ll)(n2);i++)
#define put(a) cout<<a<<"\n"
#define all(a)  (a).begin(),(a).end()
#define SORT(a) sort((a).begin(),(a).end())
#define oorret 0
#define oor(x) [&](){try{x;} catch(const out_of_range& oor){return oorret;} return x;}()
#define SZ(x) ((ll)(x).size())
typedef long long ll;
typedef pair<int, int> P;
template<typename T1,typename T2> inline bool chmin(T1 &a,T2 b){if(a>b){a=b;return 1;}return 0;}
template<typename T1,typename T2> inline bool chmax(T1 &a,T2 b){if(a<b){a=b;return 1;}return 0;}

class Modulo{
private:
    ll mod = 1e9+7;
    vector<ll> factable = {1};
    vector<ll> invtable = {1};
    
public:
    Modulo(ll _val){
        val = _val;
    }
    Modulo(){
        val = 0;
    }
    Modulo(ll _val,ll _mod){
        val = _val;
        mod = _mod;
    }
    ll val;
    //static const ll mod = 1e9+7;
    ll pro(ll x,ll y){return ((x%mod)*(y%mod))%mod;}
    ll sum(ll x,ll y){return ((x%mod)+(y%mod))%mod;}
    ll dif(ll x,ll y){ll d =((x%mod)-(y%mod))%mod;if(d>=0){return d;}else{return d+mod;}}
    ll quo(ll x, ll y){return pro(x,pow(y,mod-2));}
    ll pow(ll x,ll y){
        if(y<=0){return 1;}
        if(y%2==0){ll d = pow(x,y/2);return ((d%mod)*(d%mod))%mod;}
        else{return (x*pow(x,y-1))%mod;}
    }
    void operator=(ll n){this->val = n%mod;}
    ll operator+(ll n){return sum(this->val,n);}
    ll operator-(ll n){return dif(this->val,n);}
    ll operator*(ll n){return pro(this->val,n);}
    ll operator/(ll n){return quo(this->val,n);}
    void operator+=(ll n){this->val = sum(this->val,n);}
    void operator-=(ll n){this->val = dif(this->val,n);}
    void operator*=(ll n){this->val = pro(this->val,n);}
    void operator/=(ll n){this->val = quo(this->val,n);}
    ll fac(ll x){
        //x! mod mod
        if(factable.size()<=x){
            ll s = factable.size();
            FOR(i,s,x+1){
                factable.push_back(pro(i,factable.back()));
                invtable.push_back(quo(1,factable.back()));
            }
        }
        if(x<0) return 1;
        else return factable[x];
    }
    ll facinv(ll x){
        if(invtable.size()<=x){
            ll s = invtable.size();
            FOR(i,s,x+1){
                factable.push_back(pro(i,factable.back()));
                invtable.push_back(quo(1,factable.back()));
            }
        }
        if(x<0) return 1;
        else return invtable[x];
    }
    ll com(ll x,ll y){
        //xCy mod mod = x!/((x-y)!*y!) mod mod
        if(x-y<y)return com(x,x-y);
        return pro(fac(x),pro(facinv(x-y),facinv(y)));
    }
};

int main(){
    int n;
    cin >> n;
    vector<int> a(n);
    REP(i,n){
        cin >> a[i];
    }
    Modulo m;
    if(n%2==0){
        bool cor = true;
        SORT(a);
        REP(i,n/2){
            if(a[i*2]==a[i*2+1]&&a[i*2]==(2*i+1)){
                
            }else{
                cor = false;
                break;
            }
        }
        if(cor){
            m = m.pow(2,n/2);
        }
    }else{
        bool cor = true;
        a.push_back(0);
        SORT(a);
        REP(i,(n+1)/2){
            if(a[i*2]==a[i*2+1]&&a[i*2]==2*i){
                
            }else{
                cor = false;
                break;
            }
        }
        if(cor){
            m = m.pow(2,n/2);
        }
    }
    put(m.val);
    return 0;
}


Measured memory_bytes: 896