TLE......

#include<bits/stdc++.h>
using namespace std;
int a[10000001],b[10000001],sum[10000001],lena,lenb,len,s,i,j;
int main()
{
    string a1,b1;
	cin>>a1>>b1;
	lena=a1.size(); 
	lenb=b1.size();
	for(i=0;i<lena;i++)a[i]=a1[lena-1-i]-'0';
	for(i=0;i<lenb;i++)b[i]=b1[lenb-1-i]-'0';
	for(i=0;i<lenb;i++)
    {
		for(j=0;j<lena||s!=0;j++)
        {
			sum[i+j]+=a[j]*b[i]+s;
			s=sum[i+j]/10;
			sum[i+j]%=10;
		}
	}
	len=i+j;
	while(sum[len]==0&&len>0)len--;
	for(i=len;i>=0;i--)cout<<sum[i];
	return 0;
}