#include <bits/stdc++.h>

using namespace std;

typedef pair<int, int> pii;
typedef pair<int, pair<int, int> > piii;
typedef long long ll;
const int N = 2000086, MOD = 998244353, INF = 0x3f3f3f3f;
ll res;
int n, m, cnt, w[N];


ll fac[N], inv[N];
inline ll qmi(ll a, ll b, ll c) { ll res = 1; while (b) { if (b & 1) res = res * a % c; a = a * a % c; b >>= 1; } return res; }
inline void init() {
    fac[0] = 1;
    for (int i = 1; i < N; i++) fac[i] = fac[i - 1] * i % MOD;
    inv[N - 1] = qmi(fac[N - 1], MOD - 2, MOD);
    for (int i = N - 2; i > -1; i--) inv[i] = inv[i + 1] * (i + 1) % MOD;
}

ll C(int a, int b) { return fac[a] * inv[b] % MOD * inv[a - b] % MOD; }

char s[N];

int main() {
    init();
    cin >> n;
    scanf("%s", s + 1);
    if (s[1] == s[2]) {
        for (int i = 0; i <= n; i += 2) {
            res = (res + C(n >> 1, i >> 1) % MOD * C(n >> 1, i >> 1)) % MOD;
        }
        printf("%lld\n", res);
    } else {
        for (int i = 0; i <= n; i += 2) {
            res = (res + C(n >> 1, i >> 1)) % MOD;
        }
        printf("%lld\n", res);
    }
    return 0;
}