Factorial of a Big Number

/*
 * Problem : Compute n! exactly.
 * Input   : One integer n.
 * Output  : n! as digits.
 * Approach: Use big integers.
 * Time    : O(n * digits)
 * Space   : O(digits)
 * Java    : 8 or newer.
 */
import java.util.Scanner;
import java.math.BigInteger;

public class Main {
    // This method solves the task. It receives the input and returns the answer.
    static String solve(long n) {
        // Step 1: BigInteger can hold any number of digits. Start at 1.
        BigInteger result = BigInteger.ONE;

        // Step 2: Multiply by 2, 3, ..., n.
        for (long i = 2; i <= n; i++) {
            result = result.multiply(BigInteger.valueOf(i));
        }
        return result.toString();
    }

    public static void main(String[] args) {
        long n = new Scanner(System.in).nextLong();
        System.out.println(solve(n));
    }
}