#include <iostream> #include <string> #include <vector> using namespace std; using i64 = long long; constexpr int MOD = 998244353; struct mint { int val; mint() : val(0) { } mint(i64 x) : val(x % MOD) { if (val < 0) val += MOD; } static mint raw(int x) { mint res; res.val = x; return res; } friend mint operator+(const mint& lhs, const mint& rhs) { return lhs.val + rhs.val; } friend mint operator-(const mint& lhs, const mint& rhs) { return lhs.val - rhs.val; } friend mint operator*(const mint& lhs, const mint& rhs) { return i64(lhs.val) * rhs.val; } friend mint& operator+=(mint& lhs, const mint& rhs) { return lhs = lhs + rhs; } friend mint& operator-=(mint& lhs, const mint& rhs) { return lhs = lhs - rhs; } friend mint& operator*=(mint& lhs, const mint& rhs) { return lhs = lhs * rhs; } }; int n, m; string S, P; vector<vector<vector<mint>>> f; mint solve(int i, int l, int r) { if (l > r) return 1; else if (i == 0) return l > r; else if (f[i][l][r].val < MOD) return f[i][l][r]; f[i][l][r] = solve(i - 1, l, r); for (int j = l; j <= r; ++j) { if (S[i] == P[j]) f[i][l][r] += solve(i - 1, l, j - 1) * solve(i - 1, j + 1, r); f[i][l][r] += solve(i - 1, l, j) * solve(i - 1, j + 1, r); } return f[i][l][r]; } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr); cin >> n >> m >> S >> P; S = ' ' + S; P = ' ' + P; f.resize(n + 1, vector<vector<mint>>(m + 2, vector<mint>(m + 2, mint::raw(MOD)))); cout << solve(n, 1, m).val << '\n'; return 0; }