#include <cstdio>
#include <set>

using namespace std;

typedef long long ll;

//#define MAX 8
#define MAX 65536

char a[MAX];
int sa[6];
int n,q;
#define N  998244353

template<int MMAX>
struct Matrix {
    ll a[MMAX][MMAX] = {};  
    void zero() {
        for(int i=0;i<MMAX;i++) 
            for(int j=0;j<MMAX;j++) a[i][j]=0;
    }
    void one() {
        zero();
        for(int i=0;i<MMAX;i++) a[i][i]=1;
    }
    void setRow(int row, int v[MMAX]) {
        for(int i=0;i<MMAX;i++) a[row][i]=v[i];
    }
    void oneAndCol(int col, int v[]) {
        one();
        for(int i=0;i<MMAX;i++) a[i][col]=v[i];
    }
    void oneAndCol2(int col, ll v) {
        one();
        for(int i=0;i<MMAX;i++) a[i][col]=(v>>(i))&1;
    }
    void mul(const Matrix &x, const Matrix &y) {
        for (int i = 0; i < MMAX; i++) {
            for (int j = 0; j < MMAX; j++) {
                a[i][j] = 0;
            }
        }
                for (int k = 0; k < MMAX; k++) {
            for (int j = 0; j < MMAX; j++) {
        for (int i = 0; i < MMAX; i++) {
                    a[i][j] = (a[i][j] + x.a[i][k] * y.a[k][j])%N;
                }
            }
        }

    }
    void print() {
        for(int i=0;i<MMAX;i++) {
            for(int j=0;j<MMAX;j++) {
                printf("%lld ",a[i][j]);
            }
            printf("\n");
        }
    }
};

Matrix<7> perm[2*MAX];
Matrix<7> permOp[6];

Matrix<6> count1[2*MAX];

#define D2(x) 
#define D1(x)  
#define D11(x) 

ll calcPerm() {
    int ones7[] =  {1,1,1,1,1,1,1};
    int ones6[] =  {1,1,1,1,1,1,0};
    for(int i=0;i<6;i++) permOp[i].oneAndCol(i, ones7);

    perm[MAX].a[0][6] = 1;
    for(int i=1;i<=n;i++) perm[MAX+i] = permOp[a[i]];
    perm[MAX+n+1].oneAndCol(0,ones6);
    for(int i=n+2;i<MAX;i++) perm[MAX+i].one();
    for(int i=MAX-1;i>0;i--) perm[i].mul(perm[2*i], perm[2*i+1]);

    D2(for(int i=0;i<2*MAX;i++) {
        printf("%d <-----\n",i);
        perm[i].print();
    })
    D2(printf("resP: %lld\n", perm[1].a[0][0]));
    return perm[1].a[0][0];
}

const ll found_mask[6] =  {
    0b000001000001000001000001000001000001,
    0b000010000010000010000010000010000010,
    0b000100000100000100000100000100000100,
    0b001000001000001000001000001000001000,
    0b010000010000010000010000010000010000,
    0b100000100000100000100000100000100000 };
const ll found_mask2[6] =  {
    0b111111111111111111111111111111000000,
    0b111111111111111111111111000000111111,
    0b111111111111111111000000111111111111,
    0b111111111111000000111111111111111111,
    0b111111000000111111111111111111111111,
    0b000000111111111111111111111111111111};

#define D12(x) 

set<int>  uuu;

void updateCount1(int pos) {

    {
        int fpos[6] = {};
        ll mask_init = 0b111111111111111111111111111111111111, mask;
        ll found1=0, found2=0, foundP;
        for(int c=0;c<6;c++) if(sa[c]<=0) mask_init &= found_mask2[c];

        mask = mask_init;
        for(int p = pos-1;  p>0  && mask ;p--) {
            found1|=(found_mask[a[p]]) & mask;
            mask &= found_mask2[a[p]];
        }

        mask = mask_init;
        for(int p = pos+1;  p<=n && mask;p++) {
            int c = a[p];
            found2|=(found_mask[c]) & mask;
            mask &= found_mask2[c];
            if (!fpos[c]) fpos[c] = p;
        }
        foundP = found_mask[a[pos]];

        D12(
            printf("mask_init: %llu\n", mask_init);
            for(int c=0;c<6;c++)
                printf("char: %c p:%d found1: %llu found2: %llu\n", 'a'+c, fpos[c], found1, found2);
        )

        {
            for(int c=0;c<6;c++) {
                if (c == a[pos]) continue;
                int p = fpos[c];
                if(p>0 && p <= n) {
                    ll fc = ((found1 | foundP | found2) >> (c*6)) & 0b111111;
                    count1[MAX+p].oneAndCol2(c, fc);
                    uuu.insert((MAX+p)/2);
                } 
            }
        }

        {
            int c = a[pos];
            int p = pos;
            ll fc = ((found1 | foundP) >> (c*6)) & 0b111111;
            count1[MAX+p].oneAndCol2(c, fc);
            uuu.insert((MAX+p)/2);
        }
        
        {
            int c = a[pos];
            int p = fpos[c];
            if (p > 0 && p<=n) {
                ll fc = ((foundP | found2) >> (c*6)) & 0b111111;
                count1[MAX+p].oneAndCol2(c, fc);
                uuu.insert((MAX+p)/2);
            }
        }

        while(!uuu.empty()) {
            auto it = std::prev(uuu.end());
            int i = *it;
            uuu.erase(it);
            count1[i].mul(count1[2*i], count1[2*i+1]); 
            if (i/2 > 0) uuu.insert(i/2);
        }
    }
    D11(for(int i=0;i<2*MAX;i++) {
        printf("%d <-----\n",i);
        count1[i].print();
    })

}
    
ll calcCount1() {
    int ones6[] =  {1,1,1,1,1,1};
    count1[MAX].setRow(0, ones6);

    ll last[6] = {1,1,1,1,1,1}, found = 0, found_all=0;

    for(int i=1;i<=n;i++) {
        int c = a[i];
        
        found |= found_mask[c];
        ll fc = (found >> (c*6)) & 0b111111;
        count1[MAX+i].oneAndCol2(c, fc);
        found = found & found_mask2[c];
    }
    for(int i=n+1;i<MAX;i++) count1[MAX+i].one();
    for(int i=MAX-1;i>0;i--) count1[i].mul(count1[2*i], count1[2*i+1]);

    ll res = 0;
    for(int i=0;i<6;i++) res += (sa[i]>0?count1[1].a[0][i]: 0);
    res = res %N;
    D1(printf("res: %lld\n", res);)
    D1(for(int i=0;i<2*MAX;i++) {
        printf("%d <-----\n",i);
        count1[i].print();
    })

    return res;
}

ll getCalc() {
    ll res = perm[1].a[0][0], res2 = 0;
    for(int i=0;i<6;i++) res2 += (sa[i]>0?count1[1].a[0][i]: 0);
    return (res +N - (res2%N))%N;
}
ll calc() {
    calcPerm();
    calcCount1();
    return getCalc();
}

int main() {
    scanf("%d %d",&n,&q);
    scanf(" %s", a+1);
    for(int i=1;i<=n;i++) a[i]-='a';
    for(int i=1;i<=n;i++) sa[a[i]]++;
    printf("%lld\n", calc());
    for(int i=0;i<q;i++) {
        int pos;
        char c;
        scanf("%d %c", &pos, &c);
        if (c -'a' != a[pos]) {
            sa[a[pos]]--;
            a[pos] = c-'a';
            sa[a[pos]]++;
            perm[MAX+pos] = permOp[a[pos]];
            for(int i=(MAX+pos)/2;i>0;i/=2) perm[i].mul(perm[2*i], perm[2*i+1]);
            updateCount1(pos);
            //calcCount1();
        }
        printf("%lld\n", getCalc());
    }
}