代码：

#include<bits/stdc++.h>
using namespace std;
const int N = 1e5+5;
int c[N];
int main()
{
	string a,b;
	cin >> a >> b;
	while(a.size()<b.size())
	{
		a = "0"+a;
	}
	while(b.size()<a.size())
	{
		b = "0"+b;
	}
	for(int i = 0;i<a.size();i++)
	{
		for(int j = 0;j<b.size();j++)
		{
			c[i+j]+=(a[i]-'0')*(b[j]-'0');
		}
	}
	for(int i = 0;i<=a.size()+b.size()-2;i++)
	{
		if(c[i]>9)
		{
			c[i+1]+=c[i]/10;
			c[i]%=10;
		}
	}
	stack<int>s;
	for(int i = 0;i<=a.size()+b.size()-1;i++)
	{
		s.push(c[i]);
	}
	int flag = 0;
	while(s.size())
	{
		int t = s.top();
		s.pop();
		if(flag!=0||t!=0||s.size() == 0)
		{
			flag = 1;
			printf("%d",t);
		}
	}
	return 0;
}