int longestSubsequence(string x, string y) {
    int n = x.size(), m = y.size();
    vector<vector<int>> dp(n + 1, vector<int>(m + 1, 0));

    // Compute the longest common subsequence that is also a substring
    int maxLength = 0;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= m; j++) {
            if (x[i - 1] == y[j - 1]) {
                dp[i][j] = dp[i - 1][j - 1] + 1;
                maxLength = max(maxLength, dp[i][j]);
            }
        }
    }

    return maxLength;
}