java大整數模板

import java.util.*;    
import java.io.*;    
import java.math.*;  
public class Main    
{    
    public static void main(String args[])    
    {    
        Scanner in = new Scanner(System.in);  
        BigInteger N,D,x,y,four,n18,one,gg;  
        while(in.hasNext()){  
            int n, d;  
            n = in.nextInt();  
            d = in.nextInt();  
            if(n == 1 && d == 1){
            System.out.println(0);	
            continue;
            }
			N = BigInteger.valueOf(n); 
            D = BigInteger.valueOf(d);  
            four = BigInteger.valueOf(4); 
            n18 = BigInteger.valueOf(18);  
            one = BigInteger.valueOf(1);  
            x = (N.add(four)).multiply(N.add(four)).multiply(D).multiply(D.add(one.negate()));
            y = n18.multiply(N.pow(d));
            if(x.equals(y))System.out.println("1");
            else{
            gg = x.gcd(y);
            System.out.print(x.divide(gg));
            System.out.print("/");
            System.out.println(y.divide(gg));
            }
        }  
    }  
}