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

template <int mod> struct static_modint {
    using mint = static_modint;
    int x;

    static_modint() : x(0) {}
    static_modint(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}

    mint &operator+=(const mint &rhs) {
        if ((x += rhs.x) >= mod) x -= mod;
        return *this;
    }
    mint &operator-=(const mint &rhs) {
        if ((x += mod - rhs.x) >= mod) x -= mod;
        return *this;
    }
    mint &operator*=(const mint &rhs) {
        x = (int)(1LL * x * rhs.x % mod);
        return *this;
    }
    mint &operator/=(const mint &rhs) { return *this = *this * rhs.inv(); }

    mint pow(long long n) const {
        mint _x = *this, r = 1;
        while (n) {
            if (n & 1) r *= _x;
            _x *= _x;
            n >>= 1;
        }
        return r;
    }
    mint inv() const { return pow(mod - 2); }

    mint operator+() const { return *this; }
    mint operator-() const { return mint() - *this; }
    friend mint operator+(const mint &lhs, const mint &rhs) { return mint(lhs) += rhs; }
    friend mint operator-(const mint &lhs, const mint &rhs) { return mint(lhs) -= rhs; }
    friend mint operator*(const mint &lhs, const mint &rhs) { return mint(lhs) *= rhs; }
    friend mint operator/(const mint &lhs, const mint &rhs) { return mint(lhs) /= rhs; }
    friend bool operator==(const mint &lhs, const mint &rhs) { return lhs.x == rhs.x; }
    friend bool operator!=(const mint &lhs, const mint &rhs) { return lhs.x != rhs.x; }

    friend ostream &operator<<(ostream &os, const mint &p) { return os << p.x; }
    friend istream &operator>>(istream &is, mint &a) {
        int64_t t;
        is >> t;
        a = static_modint<mod>(t);
        return (is);
    }
};

const unsigned int mod = 998244353;
using modint = static_modint<mod>;
modint mod_pow(ll n, ll x) { return modint(n).pow(x); }
modint mod_pow(modint n, ll x) { return n.pow(x); }

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n;
    cin >> n;
    vector<pair<int, int>> op1(n + 1), op2(n + 1);
    for (int i = 1; i <= n; ++i) {
        string str;
        cin >> str;
        if (str == "POP") {
            cin >> op1[i].first;
            cin >> str >> op1[i].second >> str;
        } else {
            op1[i] = {0, 0};
        }
        cin >> str >> op2[i].first >> str >> op2[i].second;
    }
    using P = pair<modint, int>;
    vector<vector<P>> dp(1025, vector<P>(n + 1));
    vector<vector<int>> used(1025, vector<int>(n + 1));
    auto calc = [&](auto calc, int a, int x) -> P {
        if (a == 0 and x == 0) {
            return {0, 0};
        }
        if (used[a][x] & 2) {
            return dp[a][x];
        }
        if (used[a][x] & 1) {
            cout << -1 << '\n';
            exit(0);
        }
        used[a][x] |= 1;

        P res;
        if (op1[x].first == a) {
            res = {1, op1[x].second};
        } else {
            auto r1 = calc(calc, op2[x].first, op2[x].second);
            auto r2 = calc(calc, a, r1.second);
            res = {r1.first + r2.first + 1, r2.second};
        }

        used[a][x] |= 2;
        return dp[a][x] = res;
    };
    auto res = calc(calc, 0, 1);
    cout << res.first << '\n';
}