UVA-568-数论

#include<iostream>
#include <stdio.h>
#include <memory.h>
using namespace std;

int main()
{
	freopen("d:\\1.txt", "r", stdin);
	int n;
	while (cin >> n)
	{
		int end = 1;
		int n2 = 0, n5 = 0;
		for(int i = 2; i <= n; i++)
		{
			int j = i;
			while (j % 2==0)
			{
				j = j / 2;
				n2++;
			}
			while (j % 5==0)
			{
				j = j / 5;
				n5++;
			}
			end = (end * j) % 10;
		}
		for(int i = 0; i < n2 - n5; i++)
		{
			end = (end * 2) % 10;
		}
		printf("%5d -> %d\n", n, end);
	}
	return 0;
}