#include <string>
#include <vector>
#include <algorithm>
#include <iostream>

std::vector<std::string> sort_size(std::string &a, std::string &b){
    if(a.size() <= b.size()){
        return {a, b};
    } else {
        return {b, a};
    }
}

void pad_zeros(std::string &input, int zeros_to_pad){
    input.insert(0, zeros_to_pad, '0');
}

std::string sum_strings(std::string a, std::string b) {
    a.erase(0, std::min(a.find_first_not_of('0'), a.size()-1));
    b.erase(0, std::min(b.find_first_not_of('0'), b.size()-1));
    auto shortest = sort_size(a, b);
    int size_diff = abs(a.size() - b.size());

    pad_zeros(shortest[0], size_diff);

    int overflow = 0;
    char insert;
    std::string result;
    for(int i=shortest[0].size()-1; i>=0; i--){
        int val1 = shortest[1][i] - '0';
        int val2 = shortest[0][i] - '0';
        int temp = val1 + val2 + overflow;
        if(temp>9){
            overflow = temp / 10;
            insert = std::to_string(temp)[1];
        } else {
            overflow = 0;
            insert = std::to_string(temp)[0];
        }
        result.insert(0, 1, insert);
    }

    if(overflow > 0)
        result.insert(0, std::to_string(overflow));

    return result;
}

int main(){
    std::string test1 = "99";
    std::string test2 = "2";
    std::cout << sum_strings(test1, test2);
}