Python1行，C++169行

Python，自带高精

print(int(input())+int(input()))

C++，编写高精度（有点过头，加减乘除和比较大小全写上了）

#include<bits/stdc++.h>
using namespace std;
class Bigint{
    private:
        string s;
    public:
        Bigint(string n){
            s=n;
            if(s.empty()) s="0";
            else{
                size_t p=s.find_first_not_of('0');
                if(p!=string::npos) s=s.substr(p);
                else s="0";
            }
        }
        Bigint(long long n){
            s="";
            while(n){
                s=char(n%10+'0')+s;
                n/=10;
            }
        }
        Bigint(){
            s="0";
        }
        string get_s(){
            return s;
        }
        friend ostream &operator<<(ostream &os,const Bigint &n){
            os<<n.s;
            return os;
        }
        friend istream &operator>>(istream &os,Bigint &n){
            os>>n.s;
            return os;
        }
        Bigint operator+(Bigint n);
        Bigint operator-(Bigint n);
        void operator++(){
            *this=*this+Bigint("1"); 
        }
        bool operator<(Bigint n){
            string str=n.s;
            if(s.size()!=str.size()) return s.size()<str.size();
            else return s<str;
        }
        bool operator>(Bigint n){
            string str=n.s;
            if(s.size()!=str.size()) return s.size()>str.size();
            else return s>str;
        }
        bool operator<=(Bigint n){
            return !(*this>n);
        }
        bool operator>=(Bigint n){
            return !(*this<n);
        }
        bool operator!=(Bigint n){
            return s!=n.s;
        }
        bool operator==(Bigint n){
            return s==n.s;
        }
        Bigint operator*(Bigint n);
        Bigint operator/(Bigint n);
        Bigint operator%(Bigint n){
            return *this-*this/n*n;
        }
};
Bigint Bigint::operator+(Bigint n){
    string s2=n.s;
    string s3=s;
    if(s.size()<s2.size()){
        while(s3.size()<s2.size()) s3='0'+s3;
    }
    else if(s3.size()>s2.size()){
        while(s2.size()<s3.size()) s2='0'+s2;
    }
    int c=0;
    string str="";
    for(long long i=0;i<s3.size();i++){
        char i1=s2[s2.size()-i-1];
        char i2=s3[s3.size()-i-1];
        int i3=i1-'0';
        int i4=i2-'0';
        int sum=i3+i4+c;
        c=sum/10;
        str=char(sum%10+'0')+str;
    }
    if(c==1) str='1'+str;
    return Bigint(str);
}
Bigint Bigint::operator*(Bigint n){
    string a=s;
    string b=n.s;
    if (a=="0"||b=="0")
        return Bigint("0");
    int lena=a.size();
    int lenb=b.size();
    vector<int> ans(lena+lenb,0);
    for(int i=lena-1;i>=0;i--){
        for(int j=lenb-1;j>=0;j--){
            int x=a[i]-'0';
            int y=b[j]-'0';
            ans[i+j+1]+=x*y;
        }
    }
    for(int i=ans.size()-1;i>0;i--) {
        ans[i-1]+=ans[i]/10;
        ans[i]%=10;
    }
    string res="";
    int idx=0;
    while(idx<ans.size() -1&&ans[idx]==0) idx++;
    for(;idx<ans.size(); idx++) res+=char(ans[idx]+'0');
    return Bigint(res);
}
Bigint Bigint::operator-(Bigint n){
    if(*this<n) return Bigint("0");
    else if(*this==n) return Bigint("0");
    else{
        string s1=s;
        string s2=n.s;
        while(s1.size()<s2.size()) s1='0'+s1;
        while(s2.size()<s1.size()) s2='0'+s2;
        string str="";
        long long n=s1.size();
        int c=0;
        for(long long i=0;i<n;i++){
            int i1=s1[n-i-1]-'0';
            int i2=s2[n-i-1]-'0';
            int sum=i1-c-i2;
            if(sum<0){
                sum+=10;
                c=1;
            }
            str=char(sum+'0')+str;
        }
        return Bigint(str);
    }
}
Bigint Bigint::operator/(Bigint n) {
    if(n==Bigint("0")) throw std::runtime_error("Division by zero");
    if(*this<n) return Bigint("0");
    string dividend=s;   
    string divisor=n.s;  
    string quotient = "";  
    Bigint current_remainder=Bigint("0"); 
    for(size_t i=0;i<dividend.size();i++){
        current_remainder=current_remainder*Bigint("10")+Bigint(string(1,dividend[i]));
        int q=0;
        while(true) {
            Bigint product=n*Bigint(to_string(q+1));
            if(product>current_remainder) {
                break;
            }
            q++;
        }
        quotient+=char(q+'0');
        current_remainder=current_remainder-(n*Bigint(to_string(q)));
    }
    return Bigint(quotient);
}
int main(){
    Bigint a,b;
    cin>>a>>b;
    cout<<a+b;
    return 0;
}