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// Arti1990, II UWr

#include <bits/stdc++.h>

#define forr(i, n)                  for(int i=0; i<n; i++)
#define FOREACH(iter, coll)         for(auto iter = coll.begin(); iter != coll.end(); ++iter)
#define FOREACHR(iter, coll)        for(auto iter = coll.rbegin(); iter != coll.rend(); ++iter)
#define lbound(P,K,FUN)             ({auto SSS=P, PPP = P-1, KKK=(K)+1; while(PPP+1!=KKK) {SSS = (PPP+(KKK-PPP)/2); if(FUN(SSS)) KKK = SSS; else PPP = SSS;} PPP;})
#define testy()                     int _tests; cin>>_tests; FOR(_test, 1, _tests)
#define CLEAR(tab)                  memset(tab, 0, sizeof(tab))
#define CONTAIN(el, coll)           (coll.find(el) != coll.end())
#define FOR(i, a, b)                for(int i=a; i<=b; i++)
#define FORD(i, a, b)               for(int i=a; i>=b; i--)
#define MP                          make_pair
#define PB                          push_back
#define ff                          first
#define ss                          second
#define deb(X)                      X;

#define M 998244353
#define INF 1000000007LL
#define SIZE 9

using namespace std;

typedef vector <vector<long long>> matrix;
typedef vector<long long> vect;

int n, m, a, S = 1;
long long ile[100007][26][2], suma[100007][2];
long long nowe[100007], dwa[100007];
vector <int> v({177});
set <int> pozycje[26];
matrix ma, mb, id, d[250007];
int byl[7];

void init()
{
    forr(i, SIZE)
    {
        id.PB(vect(9, 0));
        id[i][i] = 1;
    }

    ma.PB(vect({0, 0, 1, 0,-1, 0, 0, 0, 0}));
    ma.PB(vect({0, 1, 0, 0, 0, 0, 0, 0, 0}));
    ma.PB(vect({0, 0, 1, 0, 0, 0, 0, 0, 0}));
    ma.PB(vect({0, 0, 1, 1, 0, 0, 0, 0, 0}));
    ma.PB(vect({0, 0, 0, 0, 1, 0, 0, 0, 0}));
    ma.PB(vect({0, 0, 0, 0, 1, 1, 1, 0, 0}));
    ma.PB(vect({0, 0, 1, 0,-1, 0, 0, 0, 0}));
    ma.PB(vect({0, 0, 0, 0, 0, 0, 0, 0, 0}));
    ma.PB(vect({0, 0, 1, 0, 0, 0, 0, 0, 1}));

/*
        r[0] = (rr[2] - rr[4] + M) % M; // lasta - last2a
        r[1] = rr[1]; // lastb - last2b
        r[2] = rr[2]; // suma
        r[3] = (rr[3] + rr[2]) % M; // sumb
        r[4] = rr[4]; // sum2a
        r[5] = (rr[5] + rr[4] + rr[6]) % M; // sum2b
        r[6] = (rr[2] - rr[4] + M) % M; // roznicaa
        r[7] = 0; //rr[3] - rr[5]; // roznicab
        r[8] = (rr[8] + rr[2]) % M; // suma
*/
    mb.PB(vect({1, 0, 0, 0, 0, 0, 0, 0, 0}));
    mb.PB(vect({0, 0, 0, 1, 0,-1, 0, 0, 0}));
    mb.PB(vect({0, 0, 1, 1, 0, 0, 0, 0, 0}));
    mb.PB(vect({0, 0, 0, 1, 0, 0, 0, 0, 0}));
    mb.PB(vect({0, 0, 0, 0, 1, 1, 0, 1, 0}));
    mb.PB(vect({0, 0, 0, 0, 0, 1, 0, 0, 0}));
    mb.PB(vect({0, 0, 0, 0, 0, 0, 0, 0, 0}));
    mb.PB(vect({0, 0, 0, 1, 0,-1, 0, 0, 0}));
    mb.PB(vect({0, 0, 0, 1, 0, 0, 0, 0, 1}));

/*
        r[0] = rr[0];
        r[1] = (rr[3] - rr[5] + M) % M;
        r[2] = (rr[2] + rr[3]) % M;
        r[3] = rr[3];
        r[4] = (rr[4] + rr[5] + rr[7]) % M;
        r[5] = rr[5];
        r[6] = 0; // rr[2] - rr[4];
        r[7] = (rr[3] + M - rr[5]) % M;
        r[8] = (rr[8] + rr[3]) % M;
*/
}

void copy(matrix &a, matrix &b)
{
    b.clear();
    for(auto el : a)
        b.PB(el);
}

void mult(matrix &a, matrix &b, matrix &c)
{
    forr(i, SIZE)
        forr(j, SIZE)
        {
            c[i][j] = 0;
            forr(k, SIZE)
                c[i][j] = (c[i][j] + a[i][k] * b[k][j]) % M;
        }
}

vect mult_v(matrix &a, vect &b)
{
    vect res(SIZE, 0);
    forr(i, SIZE)
        forr(j, SIZE)
            res[i] = (res[i] + a[i][j] * b[j]) % M;
    return res;
}
/*
int znajdz_poprzednia(int poz)
{
    auto it = pozycje[v[poz]].lower_bound(poz);
    it--;
    return *it;
}

int policz_old()
{
    long long res = 0;
    FOR(i, 1, n)
    {
        forr(c, 6)
            ile[i][c][0] = ile[i][c][1] = 0;
        suma[i][0] = suma[i][1] = 0;
    }
    FOR(i, 1, n)
    {
        int poprz = znajdz_poprzednia(i);
        cout << "poprz dla pozycji " << i << " to " << poprz << '\n';

        cout << " i: " << i << ", litera " << (char)(v[i]+'a') << '\n';
        FORD(dl, i, 1)
        {
            long long diff = suma[dl-1][0] - ile[dl][v[i]][0];
            ile[dl][v[i]][0] += diff;
            suma[dl][0] += diff;
            cout << "    na dlugosci " << dl << " i b 0 ustawil " << ile[dl][v[i]][0] << '\n';

            diff = suma[dl-1][1] - ile[dl][v[i]][1];
            ile[dl][v[i]][1] += diff;
            suma[dl][1] += diff;
            res += diff;
            cout << "    na dlugosci " << dl << " i b 1 ustawil " << ile[dl][v[i]][1] << '\n';
        }
    }

    return res;
}
*/
long long policz_brut()
{
    nowe[0] = 1;
    FOR(i, 1, n)
    {
        nowe[i] = 0;
        dwa[i] = 0;
        int poz = i-1;
        while(poz >= 0)
        {
            nowe[i] += nowe[poz];
            dwa[i] += dwa[poz];
            if(v[poz] == v[i])
                break;
            poz--;
        }
        if(poz > 0)
            dwa[poz] = nowe[poz];
        nowe[i] %= M;
        dwa[i] %= M;
    }
    //FOR(i, 1, n)
    //    cout << i << " - nowe: " << nowe[i] << ", dwa: " << dwa[i] << '\n';
    
    long long res = 0;
    FOR(i, 1, n)
    {
        res += dwa[i];
    }
    return res % M;
}

long long policz()
{
    //cout << "liczy "<< endl;
    matrix res, pom;
    copy(id, res);
    copy(id, pom);
    //cout << "przed" << endl;

    FOR(i, 1, n)
    {
        if(v[i] == 0)
            mult(res, ma, pom);
        else
            mult(res, mb, pom);
        copy(pom, res);
    }
    //cout << "po" << endl;

    vect vv({0, 0, 1, 1, 0, 0, 0, 0, 0});
    auto rv = mult_v(res, vv);
    return (rv[8] - rv[0] - rv[1] + 2*M) % M;
}

long long policz3()
{
    long long last_a = 0;
    long long last_b = 0;
    long long sum_a = 1;
    long long sum_b = 1;
    long long last2a = 0;
    long long last2b = 0;
    long long sum2a = 0;
    long long sum2b = 0;
    long long roznica_a = 0;
    long long roznica_b = 0;
    long long suma = 0;

    vector <long long> r({0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0});

    FOR(i, 1, n)
    {
        auto rr = r;
        if(v[i] == 0)
        {
            //  - r[0] + r[4] - r[1] + r[5]
            r[0] = (rr[2] - rr[4] + M) % M; // lasta - last2a
            r[1] = rr[1]; // lastb - last2b
            r[2] = rr[2]; // suma
            r[3] = (rr[3] + rr[2]) % M; // sumb
            //r[4] = rr[4]; // last2a
            //r[5] = rr[5]; // last2b
            r[4] = rr[4]; // sum2a
            r[5] = (rr[5] + rr[4] + rr[6]) % M; // sum2b
            r[6] = (rr[2] - rr[4] + M) % M; // roznicaa
            r[7] = 0; //rr[3] - rr[5]; // roznicab
            r[8] = (rr[8] + rr[2]) % M; // suma
            //cout << i << " - nowe: " << r[2] << ", podwojne: " << r[4] << '\n';
        }
        else
        {
            r[0] = rr[0];
            r[1] = (rr[3] - rr[5] + M) % M;
            r[2] = (rr[2] + rr[3]) % M;
            r[3] = rr[3];
            //r[4] = rr[4];
            //r[5] = rr[5];
            r[4] = (rr[4] + rr[5] + rr[7]) % M;
            r[5] = rr[5];
            r[6] = 0; // rr[2] - rr[4];
            r[7] = (rr[3] + M - rr[5]) % M;
            r[8] = (rr[8] + rr[3]) % M;
            //cout << i << " - nowe: " << r[3] << ", podwojne: " << r[5] << '\n';
        }
        //for(auto j : vector<int>({2, 3, 6, 7, 8, 9, 10}))
        //    cout << j << ": " << r[j] << ", ";
        //cout << '\n';
    }
    /*
    long long res = r[8];
    if(v[n] == 0)
        res = (r[8] + r[2]) - r[2] + r[6] - r[1] + r[5];
    else
        res += r[3];
    return (res - r[2] + r[6] - r[3] + r[7] + 2*M) % M;
    */
    return (r[8] - r[0] - r[1] + 2*M) % M;
}

long long policz_ab(int poz, int val)
{
    if(val == 0)
        copy(ma, d[S + poz]);
    else
        copy(mb, d[S + poz]);
    
    int nr = (S + poz)/2;
    while(nr >= 1)
    {
        mult(d[nr*2], d[nr*2+1], d[nr]);
        nr /= 2;
    }

    vect vv({0, 0, 1, 1, 0, 0, 0, 0, 0});
    auto rv = mult_v(d[1], vv);
    return (rv[8] - rv[0] - rv[1] + 2*M) % M;
}

int solve()
{
    init();

    string str;
    char c;

    cin >> n >> m;
    cin >> str;
    
    FOR(i, 1, n)
    {
        v.PB(str[i-1]-'a');
        byl[str[i-1]-'a'] = 1;
    }

    suma[0][0] = 1;

    cout << policz_brut() << '\n';

    //FOR(i, 1, n)
    //    forr(c, 2)
    //        forr(b, 2)  
    //            cout << i << ", " << c << ", " << b << ": " << ile[i][c][b] << '\n';

    vector <pair<int, int>> q;
    forr(i, m)
    {
        cin >> a >> c;
        q.PB({a, c - 'a'});
        byl[a, c-'a']++;
    }

    if(byl[2] == 0 && byl[3] == 0 && byl[4] == 0 && byl[5] == 0)
    {
        //cout << "case ab" << '\n';

        S = 1;
        while(S < n+2)
            S *= 2;

        forr(i, 2*S)
            copy(id, d[i]);

        FOR(i, 1, n)
            if(v[i] == 0)
                copy(ma, d[i+S]);
            else
                copy(mb, d[i+S]);

        FORD(i, S-1, 1)
        {
            mult(d[i*2], d[i*2+1], d[i]);
        }

        for(auto p : q)
        {
            cout << policz_ab(p.ff, p.ss) << '\n';
        }
    }
    else
    {
        //cout << "case a-f" << '\n';
        for(auto p : q)
        {

            v[p.ff] = p.ss;
            cout << policz_brut() << '\n';
        }
    }

    return 0;
}

int main()
{
    std::ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    solve();

    return 0;
}