#include <bits/stdc++.h>
using namespace std;
//using namespace atcoder;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define FOR(i, begin, end) for(int i=(begin);i<(end);i++)
#define REP(i, n) FOR(i,0,n)
#define IFOR(i, begin, end) for(int i=(end)-1;i>=(begin);i--)
#define IREP(i, n) IFOR(i,0,n)
#define Sort(v) sort(v.begin(), v.end())
#define Reverse(v) reverse(v.begin(), v.end())
#define all(v) v.begin(),v.end()
#define SZ(v) ((int)v.size())
#define Lower_bound(v, x) distance(v.begin(), lower_bound(v.begin(), v.end(), x))
#define Upper_bound(v, x) distance(v.begin(), upper_bound(v.begin(), v.end(), x))
#define chmax(a, b) a = max(a, b)
#define chmin(a, b) a = min(a, b)
#define bit(n) (1LL<<(n))
#define debug(x) cout << #x << "=" << x << endl;
#define vdebug(v) { cout << #v << "=" << endl; REP(i_debug, v.size()){ cout << v[i_debug] << ","; } cout << endl; }
#define mdebug(m) { cout << #m << "=" << endl; REP(i_debug, m.size()){ REP(j_debug, m[i_debug].size()){ cout << m[i_debug][j_debug] << ","; } cout << endl;} }
#define pb push_back
#define fi first
#define se second
#define int long long
#define INF 1000000000000000000
template<typename T> istream &operator>>(istream &is, vector<T> &v){ for (auto &x : v) is >> x; return is; }
template<typename T> ostream &operator<<(ostream &os, vector<T> &v){ for(int i = 0; i < v.size(); i++) { cout << v[i]; if(i != v.size() - 1) cout << endl; }; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, pair<T1, T2> p){ cout << '(' << p.first << ',' << p.second << ')'; return os; }
template<typename T> void Out(T x) { cout << x << endl; }
template<typename T1, typename T2> void chOut(bool f, T1 y, T2 n) { if(f) Out(y); else Out(n); }

using vec = vector<int>;
using mat = vector<vec>;
using Pii = pair<int, int>;
using v_bool = vector<bool>;
using v_Pii = vector<Pii>;

//int dx[4] = {1,0,-1,0};
//int dy[4] = {0,1,0,-1};
//char d[4] = {'D','R','U','L'};

const int mod = 1000000007;
//const int mod = 998244353;



signed main(){

    int N; cin >> N;
    string S; cin >> S;

    if(S[0] != S[N - 1]) Out(1);
    else{
        char t = S[0];
        bool ok = false;
        REP(i, N - 1) if(S[i] != t && S[i + 1] != t) ok = true;
        chOut(ok, 2, -1);
    }

    return 0;
}

#include<bits/stdc++.h>
using namespace std;
const int N=2e5+7;
const int mod=998244353;
typedef long long ll;
int fa[N];

int find(int x)
{
    return x==fa[x]?fa[x]:fa[x]=find(fa[x]);
}
ll qpow(ll a,ll b)
{
       ll res=1;
       while(b)
       {
            if(b&1)
            {
                res=(res*a)%mod;
            }
            a=(a*a)%mod;

            b/=2;

       }
       return res;
}
int main()
{
       int n;
       cin>>n;
       int a[n+10];
       for(int i=1;i<=n;i++)
          fa[i]=i;
       for(int i=1;i<=n;i++)
          cin>>a[i];
       for(int i=1;i<=n;i++)
       {
           if(find(i)!=find(a[i]))
           {
                 fa[find(i)]=find(a[i]);
           }
       }
       int cnt=0;
       for(int i=1;i<=n;i++)
          if(find(i)==i)
               cnt++;
       cout<<qpow(2,cnt)-1<<endl;
}
