Envío 6021

Código

#include<bits/stdc++.h>

#define fast_io ios_base::sync_with_stdio(false); cin.tie(NULL);

#define infinity (int) -((1<<31) + 1)

#define ll long long

using namespace std;

string big_sum(string a, string b){
    string ans = "";
    string largest, shortest;
    int carry = 0, i;
    if (a.size() > b.size()){
        largest = a;
        shortest = b;
    }
    else{
        largest = b;
        shortest = a;
    }
    for (i = shortest.size() - 1; i >= 0; i--){
        int digit_sum = (largest[i + (largest.size() - 1)] - '0') + (shortest[i] - '0') + carry;
        carry = digit_sum / 10;
        ans += (digit_sum % 10) + '0';
    }
    for (int j = (largest.size() - shortest.size() - 1); j >= 0; j--){
        int digit_sum = (largest[j] - '0') + carry;
        carry = digit_sum / 10;
        ans += (digit_sum % 10) + '0';
    }
    if (carry){
        ans += carry + '0';
    }
    reverse(ans.begin(), ans.end());
    return ans;
    

}

int main(){
    fast_io
    string a, b = "1"; cin>>a;//>>b;
    string ans = big_sum(a, b);
    cout<<ans<<endl;

}