poj-1604

#include<stdio.h>__int64 a[10001];int main(){    int i,n;    a[1]=1;    for(i=2;i<=10000;i++)    {      a[i]=(a[i-1]*i)%1000000000;      while(a[i]%10==0)   a[i]=a[i]/10;    }    while(scanf("%d",&n)!=EOF)    {        printf("%5d -> %I64d\n",n,a[n]%10);    }    return 0;}