#include <bits/stdc++.h>
using namespace std;

template<const int &MOD>
struct _m_int {
  int val;

  _m_int(int64_t v = 0) {
    if(v < 0) v = v % MOD + MOD;
    if(v >= MOD) v %= MOD;
    val = v;
  }

  static int inv_mod(int a, int m = MOD) {
    // https://en.wikipedia.org/wiki/Extended_Euclidean_algorithm#Example
    int g = m, r = a, x = 0, y = 1;

    while(r != 0) {
      int q = g / r;
      g %= r; swap(g, r);
      x -= q * y; swap(x, y);
    }
    return x < 0 ? x + m : x;
  }
  // wont work if we use #define int int64_t
  explicit operator int() const { return val; }
  explicit operator int64_t() const { return val; }

  _m_int& operator+=(const _m_int &other) {
    val -= MOD - other.val;
    if(val < 0) val += MOD;
    return *this;
  }

  _m_int& operator-=(const _m_int &other) {
    val -= other.val;
    if(val < 0) val += MOD;
    return *this;
  }

  static unsigned fast_mod(uint64_t x, unsigned m = MOD) {
#if !defined(_WIN32) || defined(_WIN64)
    return x % m;
#endif
    // Optimized mod for Codeforces 32-bit machines.
    // x must be less than 2^32 * m for this to work, so that x / m fits in a 32-bit unsigned int.
    unsigned x_high = x >> 32, x_low = (unsigned) x;
    unsigned quot, rem;
    asm("divl %4\n"
      : "=a" (quot), "=d" (rem)
      : "d" (x_high), "a" (x_low), "r" (m));
    return rem;
  }

  _m_int& operator*=(const _m_int &other) {
    val = fast_mod((uint64_t) val * other.val);
    return *this;
  }

  _m_int& operator/=(const _m_int &other) {
    return *this *= other.inv();
  }

  friend _m_int operator+(const _m_int &a, const _m_int &b) { return _m_int(a) += b; }
  friend _m_int operator-(const _m_int &a, const _m_int &b) { return _m_int(a) -= b; }
  friend _m_int operator*(const _m_int &a, const _m_int &b) { return _m_int(a) *= b; }
  friend _m_int operator/(const _m_int &a, const _m_int &b) { return _m_int(a) /= b; }

  _m_int& operator++() {
    val = val == MOD - 1 ? 0 : val + 1;
    return *this;
  }

  _m_int& operator--() {
    val = val == 0 ? MOD - 1 : val - 1;
    return *this;
  }

  // wont work if we use #define int int64_t
  _m_int operator++(int) { _m_int before = *this; ++*this; return before; }
  _m_int operator--(int) { _m_int before = *this; --*this; return before; }

  _m_int operator-() const {
    return val == 0 ? 0 : MOD - val;
  }

  bool operator==(const _m_int &other) const { return val == other.val; }
  bool operator!=(const _m_int &other) const { return val != other.val; }

  _m_int inv() const {
    return inv_mod(val);
  }

  _m_int pow(int64_t p) const {
    if(p < 0)	return inv().pow(-p);
    _m_int a = *this, result = 1;
    while(p > 0) {
      if(p & 1)	result *= a;
      a *= a;
      p >>= 1;
    }
    return result;
  }

  friend ostream& operator<<(ostream &os, const _m_int &m) {
    return os << m.val;
  }
};

const int MOD = 998244353;
using mint = _m_int<MOD>;

#define int int64_t








signed main(){	
	int n;	cin >> n;
	vector<int> a(n + 1);
	for(int i = 1; i <= n; ++i){
		char c; cin >> c;
		if(c == '-'){
			a[i] = -1;
		}else{
			int x; cin >> x;
			a[i] = x;
		}
	}
		
	mint ans = 0;
	
	for(int k = 1; k <= n; ++k){
		if(a[k] < 0) continue;
		
		int x = a[k];
		
		// dp[i][j] denotes no. of ways s.t. after i elements number of elements strictly less than x are j.
		mint dp[n+5][n+5];
		
		dp[0][0] = 1;
		
		for(int i = 1; i < k; ++i){
			if(a[i] < 0){
				for(int j = 0; j < n; ++j){
					dp[i][j] = dp[i-1][j];
					if(j == 0){
						dp[i][j] += dp[i-1][0] + dp[i-1][1];
					}else{
						dp[i][j] += dp[i-1][j+1]; 
					}
					
				}
			}else{
				for(int j = 0; j < n; ++j){
					if(a[i] > x){
						dp[i][j] = 2 * dp[i-1][j];
					}else{
						dp[i][j] = dp[i-1][j];
						if(j > 0) dp[i][j] += dp[i-1][j-1];
					}
					
				}
			}
		}
		
		for(int j = 0; j < n; ++j) dp[k][j] = dp[k-1][j];
		
		for(int i = k + 1; i <= n; ++i){
			if(a[i] < 0){
				for(int j = 0; j < n; ++j){
					dp[i][j] = dp[i-1][j];
					dp[i][j] += dp[i-1][j+1]; 
					
				}
			}else{
				for(int j = 0; j < n; ++j){
					if(a[i] >= x){
						dp[i][j] = 2 * dp[i-1][j];
					}else{
						dp[i][j] = dp[i-1][j];
						if(j > 0) dp[i][j] += dp[i-1][j-1];
					}
					
				}
			}
		}
		
		for(int i = 0; i < n; ++i) ans += mint(x) * dp[n][i];
	}
	
	cout << ans;
	
}

















