public static void lcs(String a, String b, int[][] lcs_len, int[][] mark) {
		int lena = a.length();
		int lenb = b.length();
		
		for (int i = 0; i <= lena; i++) {
			lcs_len[i][0] = 0;
		}
		
		for (int j = 0; j <= lenb; j++) {
			lcs_len[0][j] = 0;
		}
		
		for (int i = 1; i <= lena; i++) {
			for (int j = 1; j <= lenb; j++) {
				if (a.charAt(i-1) == b.charAt(j-1)) {
					lcs_len[i][j] = lcs_len[i - 1][j - 1] + 1;
					mark[i][j] = 0;
				} else {
					if (lcs_len[i][j - 1] > lcs_len[i - 1][j]) {
						lcs_len[i][j] = lcs_len[i][j - 1];
						mark[i][j] = -1;
					} else {
						lcs_len[i][j] = lcs_len[i - 1][j];
						mark[i][j] = 1;
					}
				}
			}
		}
	}