#pragma region header

#include <immintrin.h>
#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cfenv>
#include <cfloat>
#include <chrono>
#include <cinttypes>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdarg>
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <deque>
#include <fstream>
#include <functional>
#include <initializer_list>
#include <iomanip>
#include <ios>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <streambuf>
#include <string>
#include <tuple>
#include <type_traits>
#include <typeinfo>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
struct Init{Init(){std::cin.tie(0); ios::sync_with_stdio(false); cout << setprecision(20) << fixed;}} init;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
#define all(x) begin((x)), end((x))
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define uq(v) v.erase(unique(begin(v), end(v)), end(v))
template<class T> using pq = priority_queue<T>;
template<class T> using pq_g = priority_queue<T, vector<T>, greater<T>>;
template<class T> bool chmax(T &a, const T &b){if(a < b){a = b; return 1; } return 0;}
template<class T> bool chmin(T &a, const T &b){if(a > b){a = b; return 1; } return 0;}
constexpr ll INF = 2e18;
constexpr int inf = 1e9;
constexpr ld eps = 1e-15;
constexpr int dx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
constexpr int dy[8] = {0, 1 ,0, -1, 1, -1, 1, -1};



#pragma endregion header

template <uint32_t mod_, bool fast = false>
struct MontgomeryModInt {
private:
    using mint = MontgomeryModInt;
    using i32 = int32_t;
    using i64 = int64_t;
    using u32 = uint32_t;
    using u64 = uint64_t;

    static constexpr u32 get_r() {
        u32 ret = mod_;
        for (i32 i = 0; i < 4; i++) ret *= 2 - mod_ * ret;
        return ret;
    }

    static constexpr u32 r = get_r();

    static constexpr u32 n2 = -u64(mod_) % mod_;

    static_assert(r * mod_ == 1, "invalid, r * mod != 1");
    static_assert(mod_ < (1 << 30), "invalid, mod >= 2 ^ 30");
    static_assert((mod_ & 1) == 1, "invalid, mod % 2 == 0");

    u32 x;

public:
    MontgomeryModInt() : x{} {}

    MontgomeryModInt(const i64 &a): x(reduce(u64(fast ? a : (a % mod() + mod())) * n2)) {}

    static constexpr u32 reduce(const u64 &b) {
        return u32(b >> 32) + mod() - u32((u64(u32(b) * r) * mod()) >> 32);
    }

    mint &operator+=(const mint &p) {
        if (i32(x += p.x - 2 * mod()) < 0) x += 2 * mod();
        return *this;
    }

    mint &operator-=(const mint &p) {
        if (i32(x -= p.x) < 0) x += 2 * mod();
        return *this;
    }

    mint &operator*=(const mint &p) {
        x = reduce(u64(x) * p.x);
        return *this;
    }

    mint &operator/=(const mint &p) {
        *this *= p.inv();
        return *this;
    }

    mint operator-() const { return mint() - *this; }

    mint operator+(const mint &p) const { return mint(*this) += p; }

    mint operator-(const mint &p) const { return mint(*this) -= p; }

    mint operator*(const mint &p) const { return mint(*this) *= p; }

    mint operator/(const mint &p) const { return mint(*this) /= p; }

    bool operator==(const mint &p) const {
        return (x >= mod() ? x - mod() : x) == (p.x >= mod() ? p.x - mod() : p.x);
    }

    bool operator!=(const mint &p) const {
        return (x >= mod() ? x - mod() : x) != (p.x >= mod() ? p.x - mod() : p.x);
    }

    u32 val() const {
        u32 ret = reduce(x);
        return ret >= mod() ? ret - mod() : ret;
    }

    mint pow(u64 n) const {
        mint ret(1), mul(*this);
        while (n > 0) {
            if (n & 1) ret *= mul;
            mul *= mul;
            n >>= 1;
        }
        return ret;
    }

    mint inv() const { return pow(mod() - 2); }

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

    friend istream &operator>>(istream &is, mint &a) {
        i64 t;
        is >> t;
        a = mint(t);
        return is;
    }

    static constexpr u32 mod() { return mod_; }
};

template <uint32_t mod>
using modint = MontgomeryModInt<mod>;
using mint = modint<998244353>;
using modint1000000007 = modint<1000000007>;

int main(){
    int N, M; cin >> N >> M;
    string S; cin >> S;
    vector<vector<int>> H(N);
    for(int i = 0; i < M; ++i){
        int A, B; cin >> A >> B;
        H[--A].pb(--B);
        H[B].pb(A);
    }
    int cnt = 0;
    for(int i = 0; i < N; ++i) if(S[i] == '?') ++cnt;
    mint tei = 1;
    for(int i = 0; i < cnt; ++i) tei *= 26;
    mint ans = 0;
    for(int i = 0; i < N; ++i){
        int num = 0;
        if(S[i] == '?') ++num;
        else if(S[i] != 'a') continue;
        for(auto u: H[i]){
            if(S[u] == '?') ++num;
            else if(S[u] != 'o') continue;
            for(auto v: H[u]){
                if(S[v] == '?') ++num;
                else if(S[v] != 'i') continue;
                if(v == i){
                    if(S[v] == '?') --num;
                    continue;
                }
                if(num == 0) ans += tei;
                if(num == 1) ans += tei / 26;
                if(num == 2) ans += tei / (26 * 26);
                if(num == 3) ans += tei / (26 * 26 * 26);
                if(S[v] == '?') --num;
            }
            if(S[u] == '?') --num;
        }
    }
    cout << ans << "\n";
}