//#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using lint = long long;
constexpr lint mod = 1e9 + 7;
#define all(x) (x).begin(), (x).end()
#define bitcount(n) __builtin_popcountll((lint)(n))
#define fcout cout << fixed << setprecision(15)
//#define highest(x) (63 - __builtin_clzl(x))
#define rep(i, n) for(int i = 0; i < int(n); i++)
#define rep2(i, l, r) for(int i = int(l); i < int(r); i++)
#define repr(i, n) for(int i = int(n) - 1; i >= 0; i--)
#define repr2(i, l, r) for(int i = int(r) - 1; i >= int(l); i--)
#define mp(x, y) make_pair(x, y)
constexpr int inf9 = 1e9; constexpr lint inf18 = 1e18;
inline void Yes(bool condition){ if(condition) cout << "Yes" << endl; else cout << "No" << endl; }
lint power(lint base, lint exponent, lint module){ if(exponent % 2){ return power(base, exponent - 1, module) * base % module; }else if(exponent){ lint root_ans = power(base, exponent / 2, module); return root_ans * root_ans % module; }else{ return 1; }}
struct position{ int x, y; }; position mv[4] = {{0, -1}, {1, 0}, {0, 1}, {-1, 0}}; double euclidean(position first, position second){ return sqrt((second.x - first.x) * (second.x - first.x) + (second.y - first.y) * (second.y - first.y)); }
template<class T, class U> string to_string(pair<T, U> x){ return to_string(x.first) + "," + to_string(x.second); } string to_string(string x){ return x; }
template<class T> string to_string(complex<T> x){ return to_string(make_pair(x.real(), x.imag())); }
template<class itr> void array_output(itr start, itr goal){ string ans; for(auto i = start; i != goal; i++) cout << (i == start ? "" : " ") << (*i); if(!ans.empty()) ans.pop_back(); cout << ans << endl; }
template<class itr> void cins(itr first, itr last){ for(auto i = first; i != last; i++){ cin >> (*i); } }
template<class T> T gcd(T a, T b){ if(b) return gcd(b, a % b); else return a; }
template<class T> T lcm(T a, T b){ return a / gcd(a, b) * b; }
struct combination{ vector<lint> fact, inv; combination(int sz) : fact(sz + 1), inv(sz + 1){ fact[0] = 1; for(int i = 1; i <= sz; i++){ fact[i] = fact[i - 1] * i % mod; } inv[sz] = power(fact[sz], mod - 2, mod); for(int i = sz - 1; i >= 0; i--){ inv[i] = inv[i + 1] * (i + 1) % mod; } } lint P(int n, int r){ if(r < 0 || n < r) return 0; return (fact[n] * inv[n - r] % mod); } lint C(int p, int q){ if(q < 0 || p < q) return 0; return (fact[p] * inv[q] % mod * inv[p - q] % mod); } };
template<class itr> bool next_sequence(itr first, itr last, int max_bound){ itr now = last; while(now != first){ now--; (*now)++; if((*now) == max_bound){ (*now) = 0; }else{ return true; } } return false; }
template<class itr, class itr2> bool next_sequence2(itr first, itr last, itr2 first2, itr2 last2){ itr now = last; itr2 now2 = last2; while(now != first){ now--, now2--; (*now)++; if((*now) == (*now2)){ (*now) = 0; }else{ return true; } } return false; }
template<class T> bool chmax(T &a, const T &b){ if(a < b){ a = b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b){ if(b < a){ a = b; return 1; } return 0; }
inline int at(lint i, int j){ return (i >> j) & 1; }
random_device rnd;
bool is_in_board(lint y, lint x, lint H, lint W){ return (0 <= y && y < H && 0 <= x && x < W); }
lint inv2 = power(2, mod - 2, mod);

int main(){
    int n;
    string s;
    cin >> n >> s;
    if(s[0] != s.back()){
        cout << 1 << endl;
        return 0;
    }
    
    rep(i, n - 1){
        if(s[i] != s[0] && s[i + 1] != s[0]){
            cout << 2 << endl;
            return 0;
        }
    }
    cout << -1 << endl;
}

//In The Name Of Allah
#include<bits/stdc++.h>
using namespace std;

typedef long long ll;
#define pb push_back
#define F first
#define S second
//#pragma GCC optimize("Ofast")

const int maxn = 2e5 + 5, md = 998244353;

int vis[maxn], n, f[maxn], cnt;
bool c[maxn];
vector<int> cycle, adjr[maxn];
ll ans = 1;

int dfs3(int v)
{
	int A = 1;
	for(auto u : adjr[v])
		A += dfs3(u);
	
	return A;
}

void dfs2(int v)
{
	c[v] = 1;
	if(!c[f[v]])
		dfs2(f[v]);
}

void dfs(int v)
{
	vis[v] = cnt;
	if(vis[f[v]] == cnt)
		cycle.pb(f[v]);
	else if(!vis[f[v]])
		dfs(f[v]);
}

int main()
{
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin >> n;
	for(int i = 1; i <= n; i++)
	{
		cin >> f[i];
		adjr[f[i]].pb(i);
	}
	
	for(int i = 1; i <= n; i++)
		if(!vis[i])
		{
			cnt++, dfs(i);
		}
	
	
	memset(vis, 0, maxn);

	for(auto v : cycle)
		if(!c[v])
		{
			//cout << v << " ";
			dfs2(v);
			ans = ans * 2 % md;
		}
	//return 0;
	
	/*for(int i = 1; i <= n; i++)
		if(c[f[i]]&& !c[i])
		{
			ans *= dfs3(i) + 1;
			ans %= md;
		}*/

	cout << ans - 1 << '\n';

}
