PS:省赛准备大数。
import java.math.*;
import java.util.*;
public class Test {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String s1 = sc.nextLine();
String s2 = sc.nextLine();
BigInteger b1 = new BigInteger(s1);
BigInteger b2 = new BigInteger(s2);
BigInteger b3 = b2.multiply(b1);
System.out.println(b3);
}
}