#include<bits/stdc++.h>

using namespace std;

int N;
int arr[16][2];
int benefit = 0;

void ddddawang(int x, int b) {
  if(x > N){
    return;
  }

  for(int i = x; i <= N; i++) {
    if(i + arr[i][0] - 1 <= N) {
      benefit = max(benefit, b + arr[i][1]);
      ddddawang(i + arr[i][0], b + arr[i][1]);
    }
  }
}

int main() {
  cin >> N;
    
  for(int i = 1; i <= N; i++){
      cin >> arr[i][0] >> arr[i][1];
  }
   

  for(int i = 1; i <= N; i++) {
    if(i + arr[i][0] - 1 <= N) {
      benefit = max(benefit, arr[i][1]);
      ddddawang(i + arr[i][0], arr[i][1]);
    }
  }
  cout << benefit;
}