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#pragma GCC optimize ("Ofast")
#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define FOR(i, a, b) for (auto i=(a); i<(b); i++)
#define FORD(i, a,  b) for (auto i=(a); i>(b); i--)
#define SZ(x) ((int)(x).size())
#define ALL(x) (x).begin(), (x).end()
#define ithBit(m, i) ((m)>>(i) & 1)
#ifdef DEBUG
#include "debug.h"
#else
#define dbg(...) 0
#endif

template <typename T1, typename T2> inline void remin(T1& a, T2 b) { a = std::min(a, (T1)b);	}
template <typename T1, typename T2> inline void remax(T1& a, T2 b) { a = std::max(a, (T1)b);	}

const int maxN = 1 << 17, mod = 998'244'353;

struct Uniqs
{
	static constexpr int S = 6;

	int visMask, left[S], right[S];
	long long M[S][S];

	Uniqs()
	{
		FOR(i, 0, S)
		{
			std::fill(M[i], M[i] + S, 0);
			left[i] = right[i] = 1;
		}
	}

	void setup(int ind)
	{
		FOR(i, 0, S)
			M[i][i] = i == ind;
		visMask = 1 << ind;
	}

	void merge(const Uniqs& A, const Uniqs& B)
	{
		FOR(i, 0, S) FOR(j, 0, S)
		{
			M[i][j] = 0;

			if (not ithBit(A.visMask, i) or not ithBit(B.visMask, j))
				M[i][j] = (A.M[i][j] + B.M[i][j]) % mod;
			
			else FOR(a, 0, S)
			{
				FOR(b, 0, S)
					if (A.right[a] <= A.right[b] and B.left[b] <= B.left[a])
						M[i][j] += A.M[i][a] * B.M[b][j];
				M[i][j] %= mod;
			}
		}
		FOR(i, 0, S)
		{
			left[i] = A.left[i] + (!ithBit(A.visMask, i) * B.left[i]);
			right[i] = B.right[i] + (!ithBit(B.visMask, i) * A.right[i]);
		}
		visMask = A.visMask | B.visMask;
	}

	long long eval()
	{
		long long ret = 1;
		FOR(i, 0, S)
		{
			FOR(j, 0, S)
				ret += M[i][j];
			ret %= mod;
		}
		return ret;
	}
};

struct Alls
{
	static constexpr int S = 7;

	long long M[S][S];

	Alls()
	{
		FOR(i, 0, S) FOR(j, 0, S)
			M[i][j] = i == j;
	}

	void setup(int ind)
	{
		FOR(i, 0, S) FOR(j, 0, S)
			M[i][j] = i == j or j == ind;
	}

	void merge(const Alls& A, const Alls& B)
	{
		FOR(i, 0, S) FOR(j, 0, S)
		{
			M[i][j] = 0;
			FOR(k, 0, S)
				M[i][j] += A.M[i][k] * B.M[k][j];
			M[i][j] %= mod;
		}
	}
	
	long long eval()
	{
		long long ret = 0;
		FOR(j, 0, S)
			ret += M[S-1][j];
		return ret % mod;
	}
};

struct Tree
{
	int offset;
	Uniqs U[maxN];
	Alls A[maxN];

	void init(char* T, int n)
	{
		for (offset = 1; offset < n; offset *= 2)	;
		FOR(i, 0, n)
		{
			U[offset + i].setup(T[i] - 'a');
			A[offset + i].setup(T[i] - 'a');
		}
		FORD(i, offset-1, 0)
		{
			U[i].merge(U[i * 2], U[i*2+1]);
			A[i].merge(A[i*2+1], A[i * 2]);
		}
	}

	void update(int v, char x)
	{
		v += offset;
		U[v].setup(x - 'a');
		A[v].setup(x - 'a');
		for (v /= 2; v != 0; v /= 2)
		{
			U[v].merge(U[v * 2], U[v*2+1]);
			A[v].merge(A[v*2+1], A[v * 2]);
		}
	}

	long long eval()
	{
		return (A[1].eval() - U[1].eval() + mod) % mod;
	}
} tree;

char T[maxN];

void solve()
{
	int n, q;
	scanf ("%d%d%s", &n, &q, T);
	tree.init(T, n);
	printf("%lld\n", tree.eval());
	while (q--)
	{
		int i;
		char x;
		scanf ("%d %c", &i, &x);
		tree.update(--i, x);
		printf("%lld\n", tree.eval());
	}
}

int main()
{
	int tc = 1;
//	scanf ("%d", &tc);	

	FOR(cid, 1, tc+1)
		solve();
	return 0;
}