#include <vector>
#include <iostream>
#include <stdio.h>

using namespace std;

long elementsSum(const std::vector<std::vector<int> >& arr, int d = 0){
  //your code here

    long sum = 0;
    int indice = arr.size() - 1;

    for(int i = 0; i < arr.size(); i++) {

        if(arr[i].size() > 0 &&  indice >= 0 && indice  < arr[i].size()) {
            sum += arr[i][indice];
        }
        else {
            sum += d;
        }
        indice--;
    }

    return sum ;

}

int main() {

    std::vector<std::vector<int> > v;
    std::vector<int> aux1;
    aux1.push_back(-5);
    aux1.push_back(-7);
    aux1.push_back(-9);

    std::vector<int> aux2;
    aux2.push_back(-90);
    aux2.push_back(-22);
    aux2.push_back(-10);

    v.push_back(aux1);
    v.push_back(aux2);

    cout << elementsSum(v, 1) << endl;

    return 0;
}