for (j = 0; j <= n; j++)
			L[0][j] = 0;
		for (i = 1; i <= m; i++) {
			L[i][0] = 0;
			for (j = 1; j <= n; j++)
				if (a[i] != b[j])
					if (L[i-1][j] >= L[i][j-1])
						L[i][j] = L[i-1][j];
					else
						L[i][j] = L[i][j-1];
				else /* a[i] == b[j] */
					L[i][j] = 1 + L[i-1][j-1];
		}