Mermelada

#include <iostream>
#include <utility>
#include <algorithm>

#define fi first
#define se second

constexpr int MAX = 100010;

int n;
std::pair<int, int> arr[MAX];
int memo[MAX];

int solve(int i) {
   if (memo[i]) {
      return memo[i];
   }
   if (i >= n) {
      return 0;
   } else {
      int res1 = solve(i + 1);
      int res2 = 0, res3 = 0;
      if (arr[i].fi > 0) {
         res2 = arr[i].fi + solve(i + arr[i].fi);
      }
      if (arr[i].se > 0) {
         res3 = arr[i].se + solve(i + arr[i].se);
      }
      return memo[i] = std::max({ res1, res2, res3 });
   }
}

int main( ) {
   std::ios_base::sync_with_stdio(0);
   std::cin.tie(0);
   std::cout.tie(0);

   std::cin >> n;
   for (int i = 0; i < n; ++i) {
      std::cin >> arr[i].fi >> arr[i].se;
   }
   std::cout << solve(0);
}