用long不够 要用BigInteger
by yehaixin @ 2022-03-22 20:22:45
```java
import java.math.BigInteger;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
BigInteger n = scanner.nextBigInteger();
BigInteger two = new BigInteger("2");
BigInteger three = new BigInteger("3");
BigInteger four = new BigInteger("4");
BigInteger n_1 = n.subtract(BigInteger.ONE);
BigInteger n_2 = n.subtract(two);
BigInteger n_3 = n.subtract(three);
System.out.println(n.multiply(n_1).divide(two).multiply(n_2).divide(three).multiply(n_3).divide(four));
}
}
```
by magpieeeee @ 2022-04-11 12:59:22