The Last Non-zero Digit

In this problem you will be given two decimal integer number N, M. You will have to find the last non-zero digit of the PMN . This means no of permutations of N things taking M at a time. Input The input file contains several lines of input. Each line of the input file contains two integers N (0 ≤ N ≤ 20000000), M (0 ≤ M ≤ N). Input is terminated by end-of-file. Output For each line of the input file you should output a single digit, which is the last non-zero digit of PMN . For example, if PMN is 720 then the last non-zero digit is 2. So in this case your output should be 2. Sample Input 10 10 10 5 25 6 Sample Output 8 4 2