高精度*高精度

#include <iostream>
#include <cmath>
#include <vector>
using namespace std;
int main(){
    string a,b;
    cin>>a>>b;
    vector<int> x,y;
    for(int i = a.size()-1;i>=0;i--){
        x.push_back(a[i]-'0');
    }
    for(int i = b.size()-1;i>=0;i--){
        y.push_back(b[i]-'0');
    }
    vector<int> sum(x.size()+y.size()+10,0);
    for(int i = 0;i<x.size();i++){
        for(int j = 0;j<y.size();j++){
            sum[i+j] += x[i]*y[j];  
        }
    }
    int j = 0;
    for(int i = 0;i<sum.size() || j;i++){
        j += sum[i];
        sum[i] = j%10;
        j /= 10;
    }
    while(sum.size()>1 && sum.back()==0){
        sum.pop_back();
    }
    for(int i = sum.size()-1;i>=0;i--){
        cout<<sum[i];
    }
    return 0;
}