http://acm.hust.edu.cn/vjudge/contest/view.action?cid=29821#problem/D
// File Name: bo_jwolf4.cpp
// Author: rudolf
// Created Time: 2013年08月21日 星期三 16:11:33
#include<vector>
#include<list>
#include<map>
#include<set>
#include<deque>
#include<stack>
#include<bitset>
#include<algorithm>
#include<functional>
#include<numeric>
#include<utility>
#include<sstream>
#include<iostream>
#include<iomanip>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<ctime>
using namespace std;
#include <string.h>
#define MAXN 10000
int lastdigit(char* buf)
{
const int mod[20]={1,1,2,6,4,2,2,4,2,8,4,4,8,4,6,8,8,6,8,2};
int len=strlen(buf),a[MAXN],i,c,ret=1;
if (len==1)
return mod[buf[0]-'0'];
for (i=0;i<len;i++)
a[i]=buf[len-1-i]-'0';
for (;len;len-=!a[len-1])
{
ret=ret*mod[a[1]%2*10+a[0]]%5;
for (c=0,i=len-1;i>=0;i--)
c=c*10+a[i],a[i]=c/5,c%=5;
}
return ret+ret%2*5;
}
int main()
{
char n [ 10005 ] ;
while( cin >> n )
{
printf( "%5s -> %d\n" , n , lastdigit( n ) ) ;
}
return 0;
}