int longestCommonSubstring(string &A, string &B) {
    int LCSuff[A.length()+1][B.length()+1];
    int result = 0;  // To store length of the longest common substring

    /* Following steps build LCSuff[m+1][n+1] in bottom up fashion. */
    for (int i=0; i<=A.length(); i++) {
        for (int j=0; j<=B.length(); j++) {
            if (i == 0 || j == 0) {
                LCSuff[i][j] = 0;
            } else if (A[i-1] == B[j-1]) {
                LCSuff[i][j] = LCSuff[i-1][j-1] + 1;
                result = max(result, LCSuff[i][j]);
            } else {
                LCSuff[i][j] = 0;
            }
        }
    }

    return result;
}