#include<stdlib.h>
#include<stdio.h>
#define MAX 10001
int the_ans[MAX]={0};
int main()
{
      int n,i;
      while(scanf("%d",&n)!=EOF)
          {
              if(the_ans[n]==0)
                 {
                     long ans=1;
                     for(int i=2; i<=n;i++)
                       {
                           ans*=i;
                           while(ans%10==0)
                             ans/=10;
                           if(ans>100000)
                             ans%=100000;
                        }
                     ans%=10;
                     the_ans[n]=ans;
                 }     
              printf("%5d -> %d\n", n, the_ans[n]);
          }
return 0;
}

請問系統哪裡不行做?