#include<bits/stdc++.h>
using namespace std;
#define ALL(x) x.begin(),x.end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define debug(v) cout<<#v<<":";for(auto x:v){cout<<x<<' ';}cout<<endl;
#define mod 998244353
using ll=long long;
const int INF=1000000000;
const ll LINF=1001002003004005006ll;
int dx[]={1,0,-1,0},dy[]={0,1,0,-1};
// ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
template<class T>bool chmax(T &a,const T &b){if(a<b){a=b;return true;}return false;}
template<class T>bool chmin(T &a,const T &b){if(b<a){a=b;return true;}return false;}

struct IOSetup{
    IOSetup(){
        cin.tie(0);
        ios::sync_with_stdio(0);
        cout<<fixed<<setprecision(12);
    }
} iosetup;
 
template<typename T1,typename T2>
ostream &operator<<(ostream &os,const pair<T1,T2>&p){
    os<<p.first<<" "<<p.second;
    return os;
}
 
template<typename T>
ostream &operator<<(ostream &os,const vector<T>&v){
    for(int i=0;i<(int)v.size();i++) os<<v[i]<<(i+1==(int)v.size()?"":" ");
    return os;
}

template<typename T1,typename T2>
istream &operator>>(istream &is,pair<T1,T2>&p){
    is>>p.first>>p.second;
    return is;
}

template<typename T>
istream &operator>>(istream &is,vector<T>&v){
    for(T &x:v)is>>x;
    return is;
}

template<ll Mod>
struct ModInt{
    long long x;
    ModInt():x(0){}
    ModInt(long long y):x(y>=0?y%Mod:(Mod-(-y)%Mod)%Mod){}
    ModInt &operator+=(const ModInt &p){
        if((x+=p.x)>=Mod) x-=Mod;
        return *this;
    }
    ModInt &operator-=(const ModInt &p){
        if((x+=Mod-p.x)>=Mod)x-=Mod;
        return *this;
    }
    ModInt &operator*=(const ModInt &p){
        x=(int)(1ll*x*p.x%Mod);
        return *this;
    }
    ModInt &operator/=(const ModInt &p){
        (*this)*=p.inverse();
        return *this;
    }
    ModInt operator-()const{return ModInt(-x);}
    ModInt operator+(const ModInt &p)const{return ModInt(*this)+=p;}
    ModInt operator-(const ModInt &p)const{return ModInt(*this)-=p;}
    ModInt operator*(const ModInt &p)const{return ModInt(*this)*=p;}
    ModInt operator/(const ModInt &p)const{return ModInt(*this)/=p;}
    ModInt operator==(const ModInt &p)const{return x==p.x;}
    ModInt operator!=(const ModInt &p)const{return x!=p.x;}
    ModInt inverse()const{
        int a=x,b=Mod,u=1,v=0,t;
        while(b>0){
            t=a/b;
            swap(a-=t*b,b);swap(u-=t*v,v);
        }
        return ModInt(u);
    }
    ModInt pow(long long n)const{
        ModInt ret(1),mul(x);
        while(n>0){
            if(n&1) ret*=mul;
            mul*=mul;n>>=1;
        }
        return ret;
    }
    friend ostream &operator<<(ostream &os,const ModInt &p){return os<<p.x;}
    friend istream &operator>>(istream &is,ModInt &a){long long t;is>>t;a=ModInt<Mod>(t);return (is);}
    static int get_mod(){return Mod;}
};
using mint=ModInt<mod>;

template<int MAX>
struct comcalc{
    vector<mint> fact,finv,inv;
    comcalc():fact(MAX),finv(MAX),inv(MAX){
        fact[0]=mint(1),fact[1]=mint(1),finv[0]=mint(1),finv[1]=mint(1),inv[1]=mint(1);
        for(int i=2;i<MAX;i++){
            fact[i]=fact[i-1]*mint(i);
            inv[i]=mint(0)-inv[mod%i]*(mint(mod/i));
            finv[i]=finv[i-1]*inv[i];
        }
    }
    mint com(int n,int k){
        if(n<k) return mint(0);
        if(n<0 or k<0) return mint(0);
        return fact[n]*(finv[k]*finv[n-k]);
    }
    mint fac(int n){
        return fact[n];
    }
    // 重複組み合わせ:n種類の物から重複を許し，k個選ぶ
    mint nHk(int n,int k){
        return com(n+k-1,k);
    }
    // 玉n区別，箱k区別，各箱1個以上O(k)
    mint F12_dis_dis_one(int n,int k){
        if(n<k)return mint(0);
        mint ret=0;
        for(int i=0;i<=k;i++){
            mint add=com(k,i)*(mint(i).pow(n));
            if((k-i)%2) ret-=add;
            else        ret+=add;
        }
        return ret;
    }
    /* sum combination(n+x, x), x=l to r
       https://www.wolframalpha.com/input/?i=sum+combination%28n%2Bx+%2Cx%29%2C+x%3Dl+to+r&lang=ja 
       check n+x < [COM_PRECALC_MAX]    */
    mint sum_of_comb(int n,int l,int r){
        if(l>r)return mint(0);
        mint ret=mint(r+1)*com(n+r+1,r+1)-mint(l)*com(l+n,l);
        ret/=mint(n+1);
        return ret;
    }
};

 
const int MAX=4010000;
using cominit=comcalc<MAX>;

const ll mod2=924844033;
using mint2=ModInt<mod2>;

using P=pair<ll,ll>;

int n;


// zero-sum ranges
mint solve(vector<int> v){
    mint ret=0;
    map<P,mint> mp;
    mint x=1;
    mint2 x2=1;
    mint y=mint(-2).inverse();
    mint2 y2=mint2(-2).inverse();
    mp[{1,1}]+=1;
    rep(i,(int)v.size()){
        x*=mint(v[i]);x2*=mint2(v[i]);
        mint need=x*y;mint2 need2=x2*y2;
        mint i2=mint(2).pow(i+1);
        ret+=mp[{need.x,need2.x}]/i2;
        mp[{x.x,x2.x}]+=i2;
    }
    return ret;
}

signed main(){
    cin>>n;
    vector<int> a(n);
    cin>>a;

    mint res=0;
    for(int i=1;i<n-1;i++)if(abs(a[i])==2){

        vector<int> v;
        for(int j=i-1;j>0;j--){
            if(abs(a[j])!=1) break;
            v.push_back(a[j]);
        }
        reverse(ALL(v));
        v.push_back(a[i]);
        for(int j=i+1;j<n-1;j++){
            if(abs(a[j])!=1) break;
            v.push_back(a[j]);
        }
        auto tmp=solve(v)*mint(2).pow(n-2);
        // cout<<tmp<<endl;
        res+=tmp;
    }

    bool f=true;
    {
        int x=1;
        rep(i,n){
            x*=a[i];
            if(x==-2){
                if(i==n-1) res+=1,f=false;
                else{
                    res+=mint(2).pow(n-2-i);
                }
            }
            if(abs(x)==0 or abs(x)>2) break;
        }
    }
    if(f){
        reverse(ALL(a));
        int x=1;
        rep(i,n){
            x*=a[i];
            if(x==-2){
                if(i==n-1) res+=1,f=false;
                else{
                    res+=mint(2).pow(n-2-i);
                }
            }
            if(abs(x)==0 or abs(x)>2) break;
        }
    }
    assert(f);
    // cout<<res<<endl;
    res/=mint(2).pow(n-1);
    cout<<res<<endl;
    return 0;
}