#include <bits/stdc++.h>   using namespace std;   int abc;   inline int rd(int l, int r) { return rand() % (r - l + 1) + l; }   const int mxn = 2e5 + 3, mod = 998244353;   long long por(long long x, int y = mod - 2) {     long long r = 1;     for (; y; y >>= 1) {       if (y & 1) r = r * x % mod;       x = x * x % mod;     }     return r;   }   int n, a[mxn], m, R[mxn], N;   long long w[2][mxn];   bool b[mxn];   bool chk() {     for (int i = 1; i <= n;) {       int x = a[i], y = x;       b[++m] = x > 1;       while (y--) {         if (a[i] != x) return 0;         ++i;       }     }     return 1;   }   struct VV {     vector<long long> a[2][2];     void ii(int s) {       a[0][0].resize(s), a[0][1].resize(s), a[1][0].resize(s), a[1][1].resize(s);     }   };   void ntt(vector<long long>& a, int n, bool tp = 0) {     for (int i = 1; i < n; ++i) R[i] = R[i >> 1] >> 1, R[i] |= (i & 1) * (n >> 1);     for (int i = 0; i < n; ++i) a[i] %= mod;     for (int i = 0; i < n; ++i)       if (i > R[i]) swap(a[i], a[R[i]]);     for (int d = 1, t = N >> 1; d < n; d *= 2, t >>= 1) {       for (int i = 0; i < n; i += d * 2)         for (int j = 0; j < d; ++j) {           long long x = a[i + j + d] * w[tp][t * j];           a[i + j + d] = (a[i + j] - x) % mod, a[i + j] = (a[i + j] + x) % mod;         }     }     if (tp) {       long long iv = por(n);       for (int i = 0; i < n; ++i) a[i] = a[i] * iv % mod;     }   }   vector<long long> d;   void NTT(vector<long long>& a, vector<long long>& b, vector<long long>& c,            int t1, int t2) {     for (int i = 0; i < n; ++i) d[i] = a[i] * b[i] % mod;     ntt(d, n, 1);     for (int i = 0; i < n; ++i)       if (d[i]) c[i] += d[i] * (t1 + 1) * (t2 + 1), c[i - 1] += d[i] * 2;     for (int i = 0; i < n; ++i) c[i] %= mod;   }   VV sol(int L, int R) {     if (L == R) {       VV r;       r.ii(2);       r.a[b[L]][b[L]][1] = 1;       return r;     }     int md = (L + R) >> 1;     VV v1 = sol(L, md), v2 = sol(md + 1, R), re;     n = 1;     while (n <= R - L + 1) n *= 2;     v1.ii(n), v2.ii(n), re.ii(n), d.resize(n);     for (int i1 = 0; i1 <= 1; ++i1)       for (int i2 = 0; i2 <= 1; ++i2)         for (int i3 = 0; i3 <= 1; ++i3)           for (int i4 = 0; i4 <= 1; ++i4) {             vector<long long>&h1 = v1.a[i1][i2], &h2 = v2.a[i3][i4];             h1[1] = (h1[1] + mod) % mod, h2[1] = (h2[1] + mod) % mod;             assert(h1[0] == 0 && h2[0] == 0);             assert(h1[1] >= 0 && h1[1] <= 1 && h2[1] >= 0 && h2[1] <= 1);             if (i1 == i2 && i3 == i4)               re.a[i1][i3][2] += h1[1] * h2[1], re.a[1][1][1] += h1[1] * h2[1];             if (i1 == i2) {               if (h1[1])                 for (int i = 2; i < n; ++i) {                   if (h2[i])                     assert(i + 1 < n), re.a[i1][i4][i + 1] += (i3 + 1) * h2[i],                         re.a[1][i4][i] += h2[i];                 }             }             if (i3 == i4) {               if (h2[1])                 for (int i = 2; i < n; ++i) {                   if (h1[i])                     assert(i + 1 < n), re.a[i1][i4][i + 1] += (i2 + 1) * h1[i],                         re.a[i1][1][i] += h1[i];                 }             }           }     for (int i = 0; i <= 1; ++i)       for (int j = 0; j <= 1; ++j) {         vector<long long>& v = v1.a[i][j];         v[1] = 0;         ntt(v, n);       }     for (int i = 0; i <= 1; ++i)       for (int j = 0; j <= 1; ++j) {         vector<long long>& v = v2.a[i][j];         v[1] = 0;         ntt(v, n);       }     for (int i1 = 0; i1 <= 1; ++i1)       for (int i2 = 0; i2 <= 1; ++i2)         for (int i3 = 0; i3 <= 1; ++i3)           for (int i4 = 0; i4 <= 1; ++i4)             NTT(v1.a[i1][i2], v2.a[i3][i4], re.a[i1][i4], i2, i3);     return re;   }   int main() {     abc = scanf( %d , &n);     for (int i = 1; i <= n; ++i) abc = scanf( %d , a + i);     if (!chk()) return puts( 0 ), 0;     N = 1;     while (N <= m) N *= 2;     assert(N < mxn && (mod - 1) % N == 0);     w[0][0] = w[1][0] = 1, w[0][1] = por(3, (mod - 1) / N),     w[1][1] = por(w[0][1]);     for (int i = 2; i < N; ++i)       w[0][i] = w[0][i - 1] * w[0][1] % mod,       w[1][i] = w[1][i - 1] * w[1][1] % mod;     VV re = sol(1, m);     long long ans = 0;     for (int i1 = 0; i1 <= 1; ++i1)       for (int i2 = 0; i2 <= 1; ++i2) {         vector<long long>& v = re.a[i1][i2];         long long jc = (m & 1) ? -1 : 1;         for (int i = 1; i <= m; ++i) {           jc *= -i, jc %= mod;           if (i == 1)             ans += v[i] * (i1 + 1) * jc % mod;           else             ans += v[i] * (i1 + 1) * (i2 + 1) * jc % mod;         }         ans %= mod;       }     printf( %lld n , (ans % mod + mod) % mod);     return 0;   }