#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;

using mint = modint998244353;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int n; cin >> n;
    mint ans = 0, tot = mint(2).pow(n) - 1;
    for (int i = 1; i <= n; i++) {
        mint sub = mint(2).pow(i) - 1;
        ans += mint(2).pow(n - i) * sub * (tot - sub);
    }
    string s, t; cin >> s >> t;
    int ls = s.size(), lt = t.size(), ll = 0;
    for (; ll < min(ls, lt); ll++) {
        if (s[ll] != t[ll]) {
            break;
        }
    }
    vector<mint> xs, xt;
    mint ss = 0, st = 0;
    for (int i = ls; i > ll; i--) {
        xs.push_back(mint(2).pow(n - i + 1) - 1 - ss);
        ss += xs.back();
    }
    for (int i = lt; i > ll; i--) {
        xt.push_back(mint(2).pow(n - i + 1) - 1 - st);
        st += xt.back();
    }
    vector<mint> all = xs;
    all.push_back(tot - ss - st);
    all.insert(all.end(), xt.rbegin(), xt.rend());
    vector<mint> rev = all; reverse(rev.begin(), rev.end());
    int sz = all.size();
    vector<mint> res = convolution(all, rev);
    for (int i = 0; i < res.size(); i++) {
        int dif = i - sz + 1;
        ans -= max(0, 2 * dif - sz) * res[i];
    }
    cout << ans.val();
}