#include <stdio.h>

const int Mod = 998244353;

long long div_mod(long long x, long long y, long long z)
{
	if (x % y == 0) return x / y;
	else return (div_mod((1 + x / y) * y - x, (z % y), y) * z + x) / y;
}

int main()
{
	int N;
	char S[100001];
	scanf("%d", &N);
	scanf("%s", S);
	
	int i, j, count[3] = {};
	long long fact[100001];
	for (i = 0; S[i] != 0; i++) count[S[i] - 'A']++;
	for (i = 1, fact[0] = 1; i <= N; i++) fact[i] = fact[i-1] * i % Mod;
	if (count[0] == 0 || count[1] == 0 || count[2] == 0) printf("1\n");
	else {
		for (i = 0; S[i] != 'A'; i++);
		if (i == 0 && S[N-1] == 'A') {
			for (i = N - 1; S[i] == 'A'; i--);
			i++;
		}
		for (j = i; S[j] == 'A'; j++) if (j == N - 1) j = -1;
		for (; S[j] == 'C'; j++) if (j == N - 1) j = -1;
		for (; S[j] == 'B'; j++) if (j == N - 1) j = -1;
		if (j != i) printf("%lld\n", (div_mod(div_mod(div_mod(fact[N], fact[count[0]], Mod), fact[count[1]], Mod), fact[count[2]], Mod) + Mod - N) % Mod);
		else printf("1\n");
	}
	fflush(stdout);
	return 0;
}