#include using namespace std; using ll = long long; using P = pair; #define rep(i, a, b) for(ll i = a; i < b; ++i) #define rrep(i, a, b) for(ll i = a; i >= b; --i) constexpr ll inf = 4e18; struct SetupIO { SetupIO() { ios::sync_with_stdio(0); cin.tie(0); cout << fixed << setprecision(30); } } setup_io; template struct StaticModint { using mint = StaticModint; static constexpr uint32_t mod() { return m; } static constexpr mint raw(uint32_t v) { mint a; a._v = v; return a; } constexpr StaticModint() : _v(0) {} template constexpr StaticModint(const T& v) { static_assert(is_integral_v); if constexpr(is_signed_v) { int64_t x = int64_t(v % int64_t(m)); if(x < 0) x += m; _v = uint32_t(x); } else _v = uint32_t(v % m); } constexpr uint32_t val() const { return _v; } constexpr mint& operator++() { return *this += 1; } constexpr mint& operator--() { return *this -= 1; } constexpr mint operator++(int) { mint res = *this; ++*this; return res; } constexpr mint operator--(int) { mint res = *this; --*this; return res; } constexpr mint& operator+=(mint rhs) { if(_v >= m - rhs._v) _v -= m; _v += rhs._v; return *this; } constexpr mint& operator-=(mint rhs) { if(_v < rhs._v) _v += m; _v -= rhs._v; return *this; } constexpr mint& operator*=(mint rhs) { return *this = *this * rhs; } constexpr mint& operator/=(mint rhs) { return *this *= rhs.inv(); } constexpr mint operator+() const { return *this; } constexpr mint operator-() const { return mint{} - *this; } constexpr mint pow(long long n) const { assert(0 <= n); if(n == 0) return 1; mint x = *this, r = 1; while(1) { if(n & 1) r *= x; n >>= 1; if(n == 0) return r; x *= x; } } constexpr mint inv() const { if constexpr(prime) { assert(_v); return pow(m - 2); } else { auto eg = inv_gcd(_v, m); assert(eg.first == 1); return eg.second; } } friend constexpr mint operator+(mint lhs, mint rhs) { return lhs += rhs; } friend constexpr mint operator-(mint lhs, mint rhs) { return lhs -= rhs; } friend constexpr mint operator*(mint lhs, mint rhs) { return uint64_t(lhs._v) * rhs._v; } friend constexpr mint operator/(mint lhs, mint rhs) { return lhs /= rhs; } friend constexpr bool operator==(mint lhs, mint rhs) { return lhs._v == rhs._v; } friend constexpr bool operator!=(mint lhs, mint rhs) { return lhs._v != rhs._v; } friend istream& operator>>(istream& in, mint& x) { long long a; in >> a; x = a; return in; } friend ostream& operator<<(ostream& out, const mint& x) { return out << x.val(); } private: uint32_t _v = 0; static constexpr bool prime = []() -> bool { if(m == 1) return 0; if(m == 2 or m == 7 or m == 61) return 1; if(m % 2 == 0) return 0; uint32_t d = m - 1; while(d % 2 == 0) d /= 2; for(uint32_t a : {2, 7, 61}) { uint32_t t = d; mint y = mint(a).pow(t); while(t != m - 1 && y != 1 && y != m - 1) { y *= y; t <<= 1; } if(y != m - 1 && t % 2 == 0) return 0; } return 1; }(); static constexpr pair inv_gcd(int32_t a, int32_t b) { if(a == 0) return {b, 0}; int32_t s = b, t = a, m0 = 0, m1 = 1; while(t) { const int32_t u = s / t; s -= t * u; m0 -= m1 * u; swap(s, t); swap(m0, m1); } if(m0 < 0) m0 += b / s; return {s, m0}; } }; using modint998244353 = StaticModint<998244353>; using modint1000000007 = StaticModint<1000000007>; using mint = modint998244353; int main(void) { int n; cin >> n; vector a(n); rep(i, 0, n) { cin >> a[i]; } vector> dp(n, vector(100001)), sdp(n, vector(100002)); rep(i, a[0], 100001) { dp[0][i] = 1; sdp[0][i + 1] = sdp[0][i] + dp[0][i]; } rep(i, 1, n) { rep(j, a[i], 100001) { dp[i][j] = sdp[i - 1][min(j, j - a[i] + a[i - 1]) + 1]; } rep(j, 0, 100001) { sdp[i][j + 1] = sdp[i][j] + dp[i][j]; } } mint ans = 0; rep(i, 0, 100001) { ans += dp[n - 1][i]; } cout << ans << '\n'; }