import org.junit.Test;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.Scanner;
public class Test1 {
//方法一：
@Test
public static void main(String[] args) {
Scanner in =new Scanner(System.in);
String str[] = in.nextLine().split(",");
char[] param1 =trim1(str[0]).toCharArray();
char[] param2 =trim1(str[1]).toCharArray();
if(param1.length >100){
System.out.println("若输入数据大于100位则只取前100位数字");
param1 = Arrays.copyOfRange(param1,0,100);
}
if(param2.length >100){
System.out.println("若输入数据大于100位则只取前100位数字");
param2 = Arrays.copyOfRange(param2,0,100);
}
String result =multiBigInt(param1, param2);
// 除去首位的0
char[] temp = result.toCharArray();
int i =0;
for (; i < temp.length; i++) {
if (temp[i] =='0')
continue;
else
break;
}
System.out.println(result.substring(i, result.length()));
in.close();
}
//计算单个字符 乘 一个字符串
public static String multiBigIntSingle(char[] a,char b) {
int pre =0;
String result ="";
for (int j = a.length -1; j >=0; j--) {
int temp = a[j] -'0';
int tempb = b -'0';
int sum = temp * tempb + pre;
pre = sum /10;
int left = sum %10;
result += left;
}
if (pre !=0)
result += pre;
char[] sb = result.toCharArray();
String value ="";
for (int j = sb.length -1; j >=0; j--)
value += sb[j];
return value;
}
public static String multiBigInt(char[] a,char[] b) {
String c ="";// 保存每一行相加后的结果
int j =0;// 控制错位
for (int i = b.length -1; i >=0; i--) {
c =addBigInt(c.toCharArray(),multiBigIntSingle(a, b[i]).toCharArray(), j++);
}
return c;
}
//将两个大整数相加 len用于控制错位相加
public static String addBigInt(char[] a,char[] b,int len) {
int maxlen = a.length + b.length;
char[] revA =reverse(a);
char[] revB =reverse(b);
String sb ="";
int tempa =0;
int tempb =0;
int pre =0;
for (int i =0; i < maxlen; i++) {
tempa =0;
tempb =0;
if (i < revA.length)
tempa = revA[i] -'0';
// 第二行要先以为len的距离 ,错位相加
if (i < revB.length + len && i >= len)
tempb = revB[i - len] -'0';
int sum = tempa + tempb + pre;
pre = sum /10;
int left = sum %10;
sb += left;
}
while (pre !=0) {
sb += pre %10;
pre /=10;
}
char[] result = sb.toCharArray();
String value ="";
for (int j = result.length -1; j >=0; j--)
value += result[j];
return value;
}
//将一个字符数组反转，便于整数相加
public static char[] reverse(char[] a) {
char[] b =new char[a.length];
int i =0;
int j = a.length -1;
for (; j >=0; j--) {
b[i] = a[j];
i++;
}
return b;
}
//去掉字符串两端空格
public static String trim1(String param){
param = param.trim();
//去全角空格
while (param.startsWith(" ")){
param = param.substring(1,param.length()).trim();
}
while (param.endsWith(" ")){
param = param.substring(0,param.length() -1).trim();
}
return param;
}
//方法二：
BigInteger res1 = BigInteger.valueOf(Long.parseLong(String.valueOf(param1))).multiply(BigInteger.valueOf(Long.parseLong(String.valueOf(param2))));
System.out.println("res="+res1);
}
