#include <bits/stdc++.h>
#define ALL(x) (x).begin(), (x).end()
#define LB(v, x) (int)(lower_bound(ALL(v), x) - v.begin())
#define UQ(v) sort(ALL(v)), (v).erase(unique(ALL(v)), (v).end())
#define IO ios::sync_with_stdio(false), cin.tie(nullptr);
#define chmax(a, b) (a) = (a) < (b) ? (b) : (a)
#define chmin(a, b) (a) = (a) < (b) ? (a) : (b)
using namespace std;
using ll = long long;
const int INF = 1e9 + 10;
const ll INFL = 4e18;

template <ll MOD>
struct ModInt {
    ll value;
    ModInt(ll x = 0) { value = (x >= 0 ? x % MOD : MOD - (-x) % MOD); }
    ModInt operator-() const { return ModInt(-value); }
    ModInt operator+() const { return ModInt(*this); }
    ModInt& operator+=(const ModInt& other) {
        value += other.value;
        if (value >= MOD) value -= MOD;
        return *this;
    }
    ModInt& operator-=(const ModInt& other) {
        value += MOD - other.value;
        if (value >= MOD) value -= MOD;
        return *this;
    }
    ModInt& operator*=(const ModInt other) {
        value = value * other.value % MOD;
        return *this;
    }
    ModInt& operator/=(ModInt other) {
        (*this) *= other.inv();
        return *this;
    }
    ModInt operator+(const ModInt& other) const { return ModInt(*this) += other; }
    ModInt operator-(const ModInt& other) const { return ModInt(*this) -= other; }
    ModInt operator*(const ModInt& other) const { return ModInt(*this) *= other; }
    ModInt operator/(const ModInt& other) const { return ModInt(*this) /= other; }
    ModInt pow(ll x) const {
        ModInt ret(1), mul(value);
        while (x) {
            if (x & 1) ret *= mul;
            mul *= mul;
            x >>= 1;
        }
        return ret;
    }
    ModInt inv() const { return pow(MOD - 2); }
    bool operator==(const ModInt& other) const { return value == other.value; }
    bool operator!=(const ModInt& other) const { return value != other.value; }
    friend ostream& operator<<(ostream& os, const ModInt& x) { return os << x.value; }
    friend istream& operator>>(istream& is, ModInt& x) {
        ll v;
        is >> v;
        x = ModInt<MOD>(v);
        return is;
    }
    static constexpr ll get_mod() { return MOD; }
};
using Mod998 = ModInt<998244353>;
using Mod107 = ModInt<1000000007>;

using mint = Mod998;

int main() {
    int N, M;
    string S;
    cin >> N >> M >> S;
    vector<vector<int>> G(N);
    for (int i = 0; i < M; i++) {
        int u, v;
        cin >> u >> v;
        u--, v--;
        G[u].push_back(v), G[v].push_back(u);
    }

    vector<mint> po(N + 1);
    po[0] = 1;
    for (int i = 1; i <= N; i++) po[i] = po[i - 1] * 26;

    int q = count(ALL(S), '?');
    mint ans = 0;
    for (int i = 0; i < N; i++) {
        if (S[i] == 'o' || S[i] == '?') {
            int d = ssize(G[i]);
            for (int j = 0; j < d; j++) {
                int a = G[i][j];
                if (S[a] == 'a' || S[a] == '?') {
                    for (int k = 0; k < d; k++) {
                        int b = G[i][k];
                        if (S[b] == 'i' || (S[b] == '?' && a != b)) {
                            int r = (S[a] == '?') + (S[i] == '?') + (S[b] == '?');
                            ans += po[q - r];
                        }
                    }
                }
            }
        }
    }

    cout << ans << endl;
}