package Practice;

import java.io.BufferedReader;

import java.io.InputStreamReader;

import java.util.StringTokenizer;

public class B14501_2 { //Åð»ç(DP)

public static void main(String[] args) throws Exception {

// TODO Auto-generated method stub

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

int N = Integer.parseInt(br.readLine());

int[] T = new int[N], P = new int[N], dp = new int[N + 1];

for(int i = 0; i < N; i++) {

StringTokenizer st = new StringTokenizer(br.readLine());

T[i] = Integer.parseInt(st.nextToken());

P[i] = Integer.parseInt(st.nextToken());

}

if(T[0] <= N) dp[T[0]] = P[0];

for(int i = 1; i < N; i++) {

dp[i] = Math.max(dp[i], dp[i - 1]);

if(i + T[i] > N) continue;

dp[i + T[i]] = Math.max(dp[i + T[i]], dp[i] + P[i]);

}

System.out.println(Math.max(dp[N], dp[N - 1]));

}

}